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Tremblay C, Aslam S, Walker JE, Lorenzini I, Intorcia AJ, Arce RA, Choudhury P, Adler CH, Shill HA, Driver-Dunckley E, Mehta S, Piras IS, Belden CM, Atri A, Beach TG, Serrano GE. RNA sequencing of olfactory bulb in Parkinson's disease reveals gene alterations associated with olfactory dysfunction. Neurobiol Dis 2024; 196:106514. [PMID: 38663633 PMCID: PMC11132317 DOI: 10.1016/j.nbd.2024.106514] [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: 02/19/2024] [Revised: 04/17/2024] [Accepted: 04/23/2024] [Indexed: 04/29/2024] Open
Abstract
The olfactory bulb is involved early in the pathophysiology of Parkinson's disease (PD), which is consistent with the early onset of olfactory dysfunction. Identifying the molecular mechanisms through which PD affects the olfactory bulb could lead to a better understanding of the pathophysiology and etiology of olfactory dysfunction in PD. We specifically aimed to assess gene expression changes, affected pathways and co-expression network by whole transcriptomic profiling of the olfactory bulb in subjects with clinicopathologically defined PD. Bulk RNA sequencing was performed on frozen human olfactory bulbs of 20 PD and 20 controls without dementia or any other neurodegenerative disorder, from the Arizona Study of Aging and Neurodegenerative disorders and the Brain and Body Donation Program. Differential expression analysis (19 PD vs 19 controls) revealed 2164 significantly differentially expressed genes (1090 upregulated and 1074 downregulated) in PD. Pathways enriched in downregulated genes included oxidative phosphorylation, olfactory transduction, metabolic pathways, and neurotransmitters synapses while immune and inflammatory responses as well as cellular death related pathways were enriched within upregulated genes. An overrepresentation of microglial and astrocyte-related genes was observed amongst upregulated genes, and excitatory neuron-related genes were overrepresented amongst downregulated genes. Co-expression network analysis revealed significant modules highly correlated with PD and olfactory dysfunction that were found to be involved in the MAPK signaling pathway, cytokine-cytokine receptor interaction, cholinergic synapse, and metabolic pathways. LAIR1 (leukocyte associated immunoglobulin like receptor 1) and PPARA (peroxisome proliferator activated receptor alpha) were identified as hub genes with a high discriminative power between PD and controls reinforcing an important role of neuroinflammation in the olfactory bulb of PD subjects. Olfactory identification test score positively correlated with expression of genes coding for G-coupled protein, glutamatergic, GABAergic, and cholinergic receptor proteins and negatively correlated with genes for proteins expressed in glial olfactory ensheathing cells. In conclusion, this study reveals gene alterations associated with neuroinflammation, neurotransmitter dysfunction, and disruptions of factors involved in the initiation of olfactory transduction signaling that may be involved in PD-related olfactory dysfunction.
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Affiliation(s)
| | - Sidra Aslam
- Banner Sun Health Research Institute, Sun City, AZ, USA
| | | | | | | | | | | | - Charles H Adler
- Department of Neurology, Mayo Clinic College of Medicine, Mayo Clinic Arizona, Scottsdale, AZ, USA
| | - Holly A Shill
- Department of Neurology, Barrow Neurological Institute, Phoenix, AZ, USA
| | - Erika Driver-Dunckley
- Department of Neurology, Mayo Clinic College of Medicine, Mayo Clinic Arizona, Scottsdale, AZ, USA
| | - Shyamal Mehta
- Department of Neurology, Mayo Clinic College of Medicine, Mayo Clinic Arizona, Scottsdale, AZ, USA
| | - Ignazio S Piras
- Neurogenomics Division, Translational Genomics Research Institute, Phoenix, AZ, USA
| | | | - Alireza Atri
- Banner Sun Health Research Institute, Sun City, AZ, USA; Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
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2
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Ma Y, Shi W, Dong Y, Sun Y, Jin Q. Spatial Multi-Omics in Alzheimer's Disease: A Multi-Dimensional Approach to Understanding Pathology and Progression. Curr Issues Mol Biol 2024; 46:4968-4990. [PMID: 38785566 PMCID: PMC11119029 DOI: 10.3390/cimb46050298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2024] [Revised: 05/14/2024] [Accepted: 05/15/2024] [Indexed: 05/25/2024] Open
Abstract
Alzheimer's Disease (AD) presents a complex neuropathological landscape characterized by hallmark amyloid plaques and neurofibrillary tangles, leading to progressive cognitive decline. Despite extensive research, the molecular intricacies contributing to AD pathogenesis are inadequately understood. While single-cell omics technology holds great promise for application in AD, particularly in deciphering the understanding of different cell types and analyzing rare cell types and transcriptomic expression changes, it is unable to provide spatial distribution information, which is crucial for understanding the pathological processes of AD. In contrast, spatial multi-omics research emerges as a promising and comprehensive approach to analyzing tissue cells, potentially better suited for addressing these issues in AD. This article focuses on the latest advancements in spatial multi-omics technology and compares various techniques. Additionally, we provide an overview of current spatial omics-based research results in AD. These technologies play a crucial role in facilitating new discoveries and advancing translational AD research in the future. Despite challenges such as balancing resolution, increasing throughput, and data analysis, the application of spatial multi-omics holds immense potential in revolutionizing our understanding of human disease processes and identifying new biomarkers and therapeutic targets, thereby potentially contributing to the advancement of AD research.
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Affiliation(s)
| | | | | | | | - Qiguan Jin
- College of Physical Education, Yangzhou University, Yangzhou 225127, China; (Y.M.); (W.S.); (Y.D.); (Y.S.)
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3
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Ribarič S. The Contribution of Type 2 Diabetes to Parkinson's Disease Aetiology. Int J Mol Sci 2024; 25:4358. [PMID: 38673943 PMCID: PMC11050090 DOI: 10.3390/ijms25084358] [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: 02/29/2024] [Revised: 03/29/2024] [Accepted: 04/11/2024] [Indexed: 04/28/2024] Open
Abstract
Type 2 diabetes (T2D) and Parkinson's disease (PD) are chronic disorders that have a significant health impact on a global scale. Epidemiological, preclinical, and clinical research underpins the assumption that insulin resistance and chronic inflammation contribute to the overlapping aetiologies of T2D and PD. This narrative review summarises the recent evidence on the contribution of T2D to the initiation and progression of PD brain pathology. It also briefly discusses the rationale and potential of alternative pharmacological interventions for PD treatment.
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Affiliation(s)
- Samo Ribarič
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia
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4
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Dorion MF, Yaqubi M, Senkevich K, Kieran NW, MacDonald A, Chen CXQ, Luo W, Wallis A, Shlaifer I, Hall JA, Dudley RWR, Glass IA, Stratton JA, Fon EA, Bartels T, Antel JP, Gan-or Z, Durcan TM, Healy LM. MerTK is a mediator of alpha-synuclein fibril uptake by human microglia. Brain 2024; 147:427-443. [PMID: 37671615 PMCID: PMC10834256 DOI: 10.1093/brain/awad298] [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: 03/08/2023] [Revised: 07/26/2023] [Accepted: 08/29/2023] [Indexed: 09/07/2023] Open
Abstract
Mer tyrosine kinase (MerTK) is a receptor tyrosine kinase that mediates non-inflammatory, homeostatic phagocytosis of diverse types of cellular debris. Highly expressed on the surface of microglial cells, MerTK is of importance in brain development, homeostasis, plasticity and disease. Yet, involvement of this receptor in the clearance of protein aggregates that accumulate with ageing and in neurodegenerative diseases has yet to be defined. The current study explored the function of MerTK in the microglial uptake of alpha-synuclein fibrils which play a causative role in the pathobiology of synucleinopathies. Using human primary and induced pluripotent stem cell-derived microglia, the MerTK-dependence of alpha-synuclein fibril internalization was investigated in vitro. Relevance of this pathway in synucleinopathies was assessed through burden analysis of MERTK variants and analysis of MerTK expression in patient-derived cells and tissues. Pharmacological inhibition of MerTK and siRNA-mediated MERTK knockdown both caused a decreased rate of alpha-synuclein fibril internalization by human microglia. Consistent with the non-inflammatory nature of MerTK-mediated phagocytosis, alpha-synuclein fibril internalization was not observed to induce secretion of pro-inflammatory cytokines such as IL-6 or TNF, and downmodulated IL-1β secretion from microglia. Burden analysis in two independent patient cohorts revealed a significant association between rare functionally deleterious MERTK variants and Parkinson's disease in one of the cohorts (P = 0.002). Despite a small upregulation in MERTK mRNA expression in nigral microglia from Parkinson's disease/Lewy body dementia patients compared to those from non-neurological control donors in a single-nuclei RNA-sequencing dataset (P = 5.08 × 10-21), no significant upregulation in MerTK protein expression was observed in human cortex and substantia nigra lysates from Lewy body dementia patients compared to controls. Taken together, our findings define a novel role for MerTK in mediating the uptake of alpha-synuclein fibrils by human microglia, with possible involvement in limiting alpha-synuclein spread in synucleinopathies such as Parkinson's disease. Upregulation of this pathway in synucleinopathies could have therapeutic values in enhancing alpha-synuclein fibril clearance in the brain.
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Affiliation(s)
- Marie-France Dorion
- Early Drug Discovery Unit, Montreal Neurological Institute-Hospital, McGill University, Montreal H3A 2B4, Canada
- Neuroimmunology Unit, Montreal Neurological Institute-Hospital, McGill University, Montreal H3A 2B4, Canada
- Department of Neurology and Neurosurgery, Montreal Neurological Institute-Hospital, McGill University, Montreal H3A 2B4, Canada
| | - Moein Yaqubi
- Neuroimmunology Unit, Montreal Neurological Institute-Hospital, McGill University, Montreal H3A 2B4, Canada
- Department of Neurology and Neurosurgery, Montreal Neurological Institute-Hospital, McGill University, Montreal H3A 2B4, Canada
| | - Konstantin Senkevich
- McGill Parkinson Program and Neurodegenerative Diseases Group, Montreal Neurological Institute-Hospital, McGill University, Montreal H3A 2B4, Canada
- Department of Human Genetics, McGill University, Montreal H3A 0C7, Canada
| | - Nicholas W Kieran
- Neuroimmunology Unit, Montreal Neurological Institute-Hospital, McGill University, Montreal H3A 2B4, Canada
| | - Adam MacDonald
- Neuroimmunology Unit, Montreal Neurological Institute-Hospital, McGill University, Montreal H3A 2B4, Canada
- Department of Neurology and Neurosurgery, Montreal Neurological Institute-Hospital, McGill University, Montreal H3A 2B4, Canada
| | - Carol X Q Chen
- Early Drug Discovery Unit, Montreal Neurological Institute-Hospital, McGill University, Montreal H3A 2B4, Canada
- Department of Neurology and Neurosurgery, Montreal Neurological Institute-Hospital, McGill University, Montreal H3A 2B4, Canada
| | - Wen Luo
- Early Drug Discovery Unit, Montreal Neurological Institute-Hospital, McGill University, Montreal H3A 2B4, Canada
- Department of Neurology and Neurosurgery, Montreal Neurological Institute-Hospital, McGill University, Montreal H3A 2B4, Canada
| | - Amber Wallis
- UK Dementia Research Institute, University College London, London WC1E 6BT, UK
| | - Irina Shlaifer
- Early Drug Discovery Unit, Montreal Neurological Institute-Hospital, McGill University, Montreal H3A 2B4, Canada
- Department of Neurology and Neurosurgery, Montreal Neurological Institute-Hospital, McGill University, Montreal H3A 2B4, Canada
| | - Jeffery A Hall
- Department of Neurology and Neurosurgery, Montreal Neurological Institute-Hospital, McGill University, Montreal H3A 2B4, Canada
| | - Roy W R Dudley
- Department of Pediatric Surgery, Division of Neurosurgery, Montreal Children's Hospital, McGill University Health Centers, Montreal H4A 3J1, Canada
| | - Ian A Glass
- Department of Pediatrics, University of Washington, Seattle, WA 98195, USA
| | | | - Jo Anne Stratton
- Neuroimmunology Unit, Montreal Neurological Institute-Hospital, McGill University, Montreal H3A 2B4, Canada
- Department of Neurology and Neurosurgery, Montreal Neurological Institute-Hospital, McGill University, Montreal H3A 2B4, Canada
| | - Edward A Fon
- Early Drug Discovery Unit, Montreal Neurological Institute-Hospital, McGill University, Montreal H3A 2B4, Canada
- Department of Neurology and Neurosurgery, Montreal Neurological Institute-Hospital, McGill University, Montreal H3A 2B4, Canada
- McGill Parkinson Program and Neurodegenerative Diseases Group, Montreal Neurological Institute-Hospital, McGill University, Montreal H3A 2B4, Canada
| | - Tim Bartels
- UK Dementia Research Institute, University College London, London WC1E 6BT, UK
| | - Jack P Antel
- Neuroimmunology Unit, Montreal Neurological Institute-Hospital, McGill University, Montreal H3A 2B4, Canada
- Department of Neurology and Neurosurgery, Montreal Neurological Institute-Hospital, McGill University, Montreal H3A 2B4, Canada
| | - Ziv Gan-or
- McGill Parkinson Program and Neurodegenerative Diseases Group, Montreal Neurological Institute-Hospital, McGill University, Montreal H3A 2B4, Canada
- Department of Human Genetics, McGill University, Montreal H3A 0C7, Canada
| | - Thomas M Durcan
- Early Drug Discovery Unit, Montreal Neurological Institute-Hospital, McGill University, Montreal H3A 2B4, Canada
- Department of Neurology and Neurosurgery, Montreal Neurological Institute-Hospital, McGill University, Montreal H3A 2B4, Canada
| | - Luke M Healy
- Neuroimmunology Unit, Montreal Neurological Institute-Hospital, McGill University, Montreal H3A 2B4, Canada
- Department of Neurology and Neurosurgery, Montreal Neurological Institute-Hospital, McGill University, Montreal H3A 2B4, Canada
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5
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Wiseman JA, Murray HC, Faull RLMF, Dragunow M, Turner CP, Dieriks BV, Curtis MA. Aggregate-prone brain regions in Parkinson's disease are rich in unique N-terminus α-synuclein conformers with high proteolysis susceptibility. NPJ Parkinsons Dis 2024; 10:1. [PMID: 38167744 PMCID: PMC10762179 DOI: 10.1038/s41531-023-00614-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Accepted: 12/01/2023] [Indexed: 01/05/2024] Open
Abstract
In Parkinson's disease (PD), and other α-synucleinopathies, α-synuclein (α-Syn) aggregates form a myriad of conformational and truncational variants. Most antibodies used to detect and quantify α-Syn in the human brain target epitopes within the C-terminus (residues 96-140) of the 140 amino acid protein and may fail to capture the diversity of α-Syn variants present in PD. We sought to investigate the heterogeneity of α-Syn conformations and aggregation states in the PD human brain by labelling with multiple antibodies that detect epitopes along the entire length of α-Syn. We used multiplex immunohistochemistry to simultaneously immunolabel tissue sections with antibodies mapping the three structural domains of α-Syn. Discrete epitope-specific immunoreactivities were visualised and quantified in the olfactory bulb, medulla, substantia nigra, hippocampus, entorhinal cortex, middle temporal gyrus, and middle frontal gyrus of ten PD cases, and the middle temporal gyrus of 23 PD, and 24 neurologically normal cases. Distinct Lewy neurite and Lewy body aggregate morphologies were detected across all interrogated regions/cases. Lewy neurites were the most prominent in the olfactory bulb and hippocampus, while the substantia nigra, medulla and cortical regions showed a mixture of Lewy neurites and Lewy bodies. Importantly, unique N-terminus immunoreactivity revealed previously uncharacterised populations of (1) perinuclear, (2) glial (microglial and astrocytic), and (3) neuronal lysosomal α-Syn aggregates. These epitope-specific N-terminus immunoreactive aggregate populations were susceptible to proteolysis via time-dependent proteinase K digestion, suggesting a less stable oligomeric aggregation state. Our identification of unique N-terminus immunoreactive α-Syn aggregates adds to the emerging paradigm that α-Syn pathology is more abundant and complex in human brains with PD than previously realised. Our findings highlight that labelling multiple regions of the α-Syn protein is necessary to investigate the full spectrum of α-Syn pathology and prompt further investigation into the functional role of these N-terminus polymorphs.
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Affiliation(s)
- James A Wiseman
- Department of Anatomy and Medical Imaging, University of Auckland, Auckland, New Zealand.
- Centre for Brain Research, University of Auckland, Auckland, 1023, New Zealand.
| | - Helen C Murray
- Department of Anatomy and Medical Imaging, University of Auckland, Auckland, New Zealand
- Centre for Brain Research, University of Auckland, Auckland, 1023, New Zealand
| | - Richard L M F Faull
- Department of Anatomy and Medical Imaging, University of Auckland, Auckland, New Zealand
- Centre for Brain Research, University of Auckland, Auckland, 1023, New Zealand
| | - Michael Dragunow
- Centre for Brain Research, University of Auckland, Auckland, 1023, New Zealand
- Department of Pharmacology, University of Auckland, Auckland, 1023, New Zealand
| | - Clinton P Turner
- LabPlus, Department of Anatomical Pathology, Te Whatu Ora, Auckland, New Zealand
| | - Birger Victor Dieriks
- Department of Anatomy and Medical Imaging, University of Auckland, Auckland, New Zealand
- Centre for Brain Research, University of Auckland, Auckland, 1023, New Zealand
| | - Maurice A Curtis
- Department of Anatomy and Medical Imaging, University of Auckland, Auckland, New Zealand.
- Centre for Brain Research, University of Auckland, Auckland, 1023, New Zealand.
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6
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Zhang N, Yan Z, Xin H, Shao S, Xue S, Cespuglio R, Wang S. Relationship among α‑synuclein, aging and inflammation in Parkinson's disease (Review). Exp Ther Med 2024; 27:23. [PMID: 38125364 PMCID: PMC10728906 DOI: 10.3892/etm.2023.12311] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Accepted: 10/19/2023] [Indexed: 12/23/2023] Open
Abstract
Parkinson's disease (PD) is a common neurodegenerative pathology whose major clinical symptoms are movement disorders. The main pathological characteristics of PD are the selective death of dopaminergic (DA) neurons in the pars compacta of the substantia nigra and the presence of Lewy bodies containing α-synuclein (α-Syn) within these neurons. PD is associated with numerous risk factors, including environmental factors, genetic mutations and aging. In many cases, the complex interplay of numerous risk factors leads to the onset of PD. The mutated α-Syn gene, which expresses pathologicalα-Syn protein, can cause PD. Another important feature of PD is neuroinflammation, which is conducive to neuronal death. α-Syn is able to interact with certain cell types in the brain, including through phagocytosis and degradation of α-Syn by glial cells, activation of inflammatory pathways by α-Syn in glial cells, transmission of α-Syn between glial cells and neurons, and interactions between peripheral immune cells and α-Syn. In addition to the aforementioned risk factors, PD may also be associated with aging, as the prevalence of PD increases with advancing age. The aging process impairs the cellular clearance mechanism, which leads to chronic inflammation and the accumulation of intracellular α-Syn, which results in DA neuronal death. In the present review, the age-associated α-Syn pathogenicity and the interactions between α-Syn and certain types of cells within the brain are discussed to facilitate understanding of the mechanisms of PD pathogenesis, which may potentially provide insight for the future clinical treatment of PD.
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Affiliation(s)
- Nianping Zhang
- Postdoctoral Mobile Station, Shandong University of Traditional Chinese Medicine, Jinan, Shandong 250355, P.R. China
- Experimental Center, Shandong University of Traditional Chinese Medicine, Jinan, Shandong 250355, P.R. China
| | - Zhaoli Yan
- Department of Neurosurgery, Affiliated Hospital of Shandong University of Traditional Chinese Medicine, Jinan, Shandong 250014, P.R. China
| | - Hua Xin
- Department of Neurology, People's Hospital of Rizhao, Rizhao, Shandong 276800, P.R. China
| | - Shuai Shao
- Department of Reproductive Medicine, Jingmen People's Hospital, Jingmen, Hubei 448000, P.R. China
| | - Song Xue
- Experimental Center, Shandong University of Traditional Chinese Medicine, Jinan, Shandong 250355, P.R. China
| | - Raymond Cespuglio
- Neuroscience Research Center of Lyon (CNRL), Claude-Bernard Lyon-1 University, 69500 Lyon, France
| | - Shijun Wang
- Department of Pathology, College of Traditional Chinese Medicine, Shandong University of Traditional Chinese Medicine, Jinan, Shandong 250355, P.R. China
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7
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Bhatia TN, Jamenis AS, Abbas M, Clark RN, Miner KM, Chandwani MN, Kim RE, Hilinski W, O'Donnell LA, Luk KC, Shi Y, Hu X, Chen J, Brodsky JL, Leak RK. A 14-day pulse of PLX5622 modifies α-synucleinopathy in preformed fibril-infused aged mice of both sexes. Neurobiol Dis 2023; 184:106196. [PMID: 37315905 PMCID: PMC10528721 DOI: 10.1016/j.nbd.2023.106196] [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: 12/01/2022] [Revised: 05/16/2023] [Accepted: 06/07/2023] [Indexed: 06/16/2023] Open
Abstract
Reactive microglia are observed with aging and in Lewy body disorders, including within the olfactory bulb of men with Parkinson's disease. However, the functional impact of microglia in these disorders is still debated. Resetting these reactive cells by a brief dietary pulse of the colony-stimulating factor 1 receptor (CSF1R) inhibitor PLX5622 may hold therapeutic potential against Lewy-related pathologies. To our knowledge, withdrawal of PLX5622 after short-term exposure has not been tested in the preformed α-synuclein fibril (PFF) model, including in aged mice of both sexes. Compared to aged female mice, we report that aged males on the control diet showed higher numbers of phosphorylated α-synuclein+ inclusions in the limbic rhinencephalon after PFFs were injected in the posterior olfactory bulb. However, aged females displayed larger inclusion sizes compared to males. Short-term (14-day) dietary exposure to PLX5622 followed by control chow reduced inclusion numbers and levels of insoluble α-synuclein in aged males-but not females-and unexpectedly raised inclusion sizes in both sexes. Transient delivery of PLX5622 also improved spatial reference memory in PFF-infused aged mice, as evidenced by an increase in novel arm entries in a Y-maze. Superior memory was positively correlated with inclusion sizes but negatively correlated with inclusion numbers. Although we caution that PLX5622 delivery must be tested further in models of α-synucleinopathy, our data suggest that larger-sized-but fewer-α-synucleinopathic structures are associated with better neurological outcomes in PFF-infused aged mice.
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Affiliation(s)
- Tarun N Bhatia
- Graduate School of Pharmaceutical Sciences, Duquesne University, Pittsburgh, PA, USA
| | - Anuj S Jamenis
- Graduate School of Pharmaceutical Sciences, Duquesne University, Pittsburgh, PA, USA
| | - Muslim Abbas
- Graduate School of Pharmaceutical Sciences, Duquesne University, Pittsburgh, PA, USA
| | - Rachel N Clark
- Graduate School of Pharmaceutical Sciences, Duquesne University, Pittsburgh, PA, USA
| | - Kristin M Miner
- Graduate School of Pharmaceutical Sciences, Duquesne University, Pittsburgh, PA, USA
| | - Manisha N Chandwani
- Graduate School of Pharmaceutical Sciences, Duquesne University, Pittsburgh, PA, USA
| | - Roxanne E Kim
- Graduate School of Pharmaceutical Sciences, Duquesne University, Pittsburgh, PA, USA
| | | | - Lauren A O'Donnell
- Graduate School of Pharmaceutical Sciences, Duquesne University, Pittsburgh, PA, USA
| | - Kelvin C Luk
- Dept. of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Yejie Shi
- Geriatric Research, Education and Clinical Center, Veterans Affairs Pittsburgh Health Care System, Pittsburgh, PA, USA; Pittsburgh Institute of Brain Disorders & Recovery and Department of Neurology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Xiaoming Hu
- Geriatric Research, Education and Clinical Center, Veterans Affairs Pittsburgh Health Care System, Pittsburgh, PA, USA; Pittsburgh Institute of Brain Disorders & Recovery and Department of Neurology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Jun Chen
- Geriatric Research, Education and Clinical Center, Veterans Affairs Pittsburgh Health Care System, Pittsburgh, PA, USA; Pittsburgh Institute of Brain Disorders & Recovery and Department of Neurology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Jeffrey L Brodsky
- Dept. of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - Rehana K Leak
- Graduate School of Pharmaceutical Sciences, Duquesne University, Pittsburgh, PA, USA.
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8
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Gorecki AM, Spencer H, Meloni BP, Anderton RS. The Poly-Arginine Peptide R18D Interferes with the Internalisation of α-Synuclein Pre-Formed Fibrils in STC-1 Enteroendocrine Cells. Biomedicines 2023; 11:2089. [PMID: 37626586 PMCID: PMC10452853 DOI: 10.3390/biomedicines11082089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Revised: 07/20/2023] [Accepted: 07/21/2023] [Indexed: 08/27/2023] Open
Abstract
In Parkinson's disease (PD), gut inflammation is hypothesised to contribute to α-synuclein aggregation, but gastrointestinal α-synuclein expression is poorly characterised. Cationic arginine-rich peptides (CARPs) are an emerging therapeutic option that exerts various neuroprotective effects and may target the transmission of protein aggregates. This study aimed to investigate endogenous α-synuclein expression in enteroendocrine STC-1 cells and the potential of the CARP, R18D (18-mer of D-arginine), to prevent internalisation of pre-formed α-synuclein fibrils (PFFs) in enteroendocrine cells in vitro. Through confocal microscopy, the immunoreactivity of full-length α-synuclein and the serine-129 phosphorylated form (pS129) was investigated in STC-1 (mouse enteroendocrine) cells. Thereafter, STC-1 cells were exposed to PFFs tagged with Alexa-Fluor 488 (PFF-488) for 2 and 24 h and R18D-FITC for 10 min. After confirming the uptake of both PFFs and R18D-FITC through fluorescent microscopy, STC-1 cells were pre-treated with R18D (5 or 10 μM) for 10 min prior to 2 h of PFF-488 exposure. Immunoreactivity for endogenous α-synuclein and pS129 was evident in STC-1 cells, with prominent pS129 staining along cytoplasmic processes and in perinuclear areas. STC-1 cells internalised PFFs, confirmed through co-localisation of PFF-488 and human-specific α-synuclein immunoreactivity. R18D-FITC entered STC-1 cells within 10 min and pre-treatment of STC-1 cells with R18D interfered with PFF uptake. The endogenous presence of α-synuclein in enteroendocrine cells, coupled with their rapid uptake of PFFs, demonstrates a potential for pathogenic spread of α-synuclein aggregates in the gut. R18D is a novel therapeutic approach to reduce the intercellular transmission of α-synuclein pathology.
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Affiliation(s)
- Anastazja M. Gorecki
- School of Health Sciences, University of Notre Dame Australia, Fremantle, WA 6160, Australia; (H.S.)
- School of Biological Sciences, University of Western Australia, Crawley, WA 6009, Australia
- Perron Institute for Neurological and Translational Science, Nedlands, WA 6009, Australia
| | - Holly Spencer
- School of Health Sciences, University of Notre Dame Australia, Fremantle, WA 6160, Australia; (H.S.)
| | - Bruno P. Meloni
- Perron Institute for Neurological and Translational Science, Nedlands, WA 6009, Australia
- Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Nedlands, WA 6009, Australia
- Department of Neurosurgery, Sir Charles Gairdner Hospital, First Floor, G-Block, QEII Medical Centre, Nedlands, WA 6008, Australia
| | - Ryan S. Anderton
- School of Health Sciences, University of Notre Dame Australia, Fremantle, WA 6160, Australia; (H.S.)
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9
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Brunert D, Quintela RM, Rothermel M. The anterior olfactory nucleus revisited - an emerging role for neuropathological conditions? Prog Neurobiol 2023:102486. [PMID: 37343762 DOI: 10.1016/j.pneurobio.2023.102486] [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: 12/23/2022] [Revised: 06/14/2023] [Accepted: 06/16/2023] [Indexed: 06/23/2023]
Abstract
Olfaction is an important sensory modality for many species and greatly influences animal and human behavior. Still, much about olfactory perception remains unknown. The anterior olfactory nucleus is one of the brain's central early olfactory processing areas. Located directly posterior to the olfactory bulb in the olfactory peduncle with extensive in- and output connections and unique cellular composition, it connects olfactory processing centers of the left and right hemispheres. Almost 20 years have passed since the last comprehensive review on the anterior olfactory nucleus has been published and significant advances regarding its anatomy, function, and pathophysiology have been made in the meantime. Here we briefly summarize previous knowledge on the anterior olfactory nucleus, give detailed insights into the progress that has been made in recent years, and map out its emerging importance in translational research of neurological diseases.
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Affiliation(s)
- Daniela Brunert
- Institute of Physiology, Medical Faculty, Otto-von-Guericke-University, 39120 Magdeburg, Germany
| | | | - Markus Rothermel
- Institute of Physiology, Medical Faculty, Otto-von-Guericke-University, 39120 Magdeburg, Germany.
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10
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Arasaratnam CJ, Song JJ, Yoshida T, Curtis MA, Graybiel AM, Faull RLM, Waldvogel HJ. DARPP-32 cells and neuropil define striosomal system and isolated matrix cells in human striatum. J Comp Neurol 2023; 531:888-920. [PMID: 37002560 PMCID: PMC10392785 DOI: 10.1002/cne.25473] [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: 07/07/2022] [Revised: 01/30/2023] [Accepted: 02/28/2023] [Indexed: 04/04/2023]
Abstract
The dorsal striatum forms a central node of the basal ganglia interconnecting the neocortex and thalamus with circuits modulating mood and movement. Striatal projection neurons (SPNs) include relatively intermixed populations expressing D1-type or D2-type dopamine receptors (dSPNs and iSPNs) that give rise to the direct (D1) and indirect (D2) output systems of the basal ganglia. Overlaid on this organization is a compartmental organization, in which a labyrinthine system of striosomes made up of sequestered SPNs is embedded within the larger striatal matrix. Striosomal SPNs also include D1-SPNs and D2-SPNs, but they can be distinguished from matrix SPNs by many neurochemical markers. In the rodent striatum the key signaling molecule, DARPP-32, is a exception to these compartmental expression patterns, thought to befit its functions through opposite actions in both D1- and D2-expressing SPNs. We demonstrate here, however, that in the dorsal human striatum, DARPP-32 is concentrated in the neuropil and SPNs of striosomes, especially in the caudate nucleus and dorsomedial putamen, relative to the matrix neuropil in these regions. The generally DARPP-32-poor matrix contains scattered DARPP-32-positive cells. DARPP-32 cell bodies in both compartments proved negative for conventional intraneuronal markers. These findings raise the potential for specialized DARPP-32 expression in the human striosomal system and in a set of DARPP-32-positive neurons in the matrix. If DARPP-32 immunohistochemical positivity predicts differential functional DARPP-32 activity, then the distributions demonstrated here could render striosomes and dispersed matrix cells susceptible to differential signaling through cAMP and other signaling systems in health and disease. DARPP-32 is highly concentrated in cells and neuropil of striosomes in post-mortem human brain tissue, particularly in the dorsal caudate nucleus. Scattered DARPP-32-positive cells are found in the human striatal matrix. Calbindin and DARPP-32 do not colocalize within every spiny projection neuron in the dorsal human caudate nucleus.
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Affiliation(s)
- Christine J Arasaratnam
- Department of Anatomy and Medical Imaging, Centre for Brain Research, University of Auckland, Auckland, New Zealand
| | - Jennifer J Song
- Department of Anatomy and Medical Imaging, Centre for Brain Research, University of Auckland, Auckland, New Zealand
| | - Tomoko Yoshida
- Department of Brain and Cognitive Sciences, McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Maurice A Curtis
- Department of Anatomy and Medical Imaging, Centre for Brain Research, University of Auckland, Auckland, New Zealand
| | - Ann M Graybiel
- Department of Brain and Cognitive Sciences, McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Richard L M Faull
- Department of Anatomy and Medical Imaging, Centre for Brain Research, University of Auckland, Auckland, New Zealand
| | - Henry J Waldvogel
- Department of Anatomy and Medical Imaging, Centre for Brain Research, University of Auckland, Auckland, New Zealand
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11
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Carceles-Cordon M, Weintraub D, Chen-Plotkin AS. Cognitive heterogeneity in Parkinson's disease: A mechanistic view. Neuron 2023; 111:1531-1546. [PMID: 37028431 PMCID: PMC10198897 DOI: 10.1016/j.neuron.2023.03.021] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 12/22/2022] [Accepted: 03/13/2023] [Indexed: 04/09/2023]
Abstract
Cognitive impairment occurs in most individuals with Parkinson's disease (PD), exacting a high toll on patients, their caregivers, and the healthcare system. In this review, we begin by summarizing the current clinical landscape surrounding cognition in PD. We then discuss how cognitive impairment and dementia may develop in PD based on the spread of the pathological protein alpha-synuclein (aSyn) from neurons in brainstem regions to those in the cortical regions of the brain responsible for higher cognitive functions, as first proposed in the Braak hypothesis. We appraise the Braak hypothesis from molecular (conformations of aSyn), cell biological (cell-to-cell spread of pathological aSyn), and organ-level (region-to-region spread of aSyn pathology at the whole brain level) viewpoints. Finally, we argue that individual host factors may be the most poorly understood aspect of this pathological process, accounting for substantial heterogeneity in the pattern and pace of cognitive decline in PD.
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Affiliation(s)
- Marc Carceles-Cordon
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Dan Weintraub
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Alice S Chen-Plotkin
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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12
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Mazzotta GM, Ceccato N, Conte C. Synucleinopathies Take Their Toll: Are TLRs a Way to Go? Cells 2023; 12:cells12091231. [PMID: 37174631 PMCID: PMC10177040 DOI: 10.3390/cells12091231] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Revised: 04/17/2023] [Accepted: 04/22/2023] [Indexed: 05/15/2023] Open
Abstract
The misfolding and subsequent abnormal accumulation and aggregation of α-Synuclein (αSyn) as insoluble fibrils in Lewy bodies and Lewy neurites is the pathological hallmark of Parkinson's disease (PD) and several neurodegenerative disorders. A combination of environmental and genetic factors is linked to αSyn misfolding, among which neuroinflammation is recognized to play an important role. Indeed, a number of studies indicate that a Toll-like receptor (TLR)-mediated neuroinflammation might lead to a dopaminergic neural loss, suggesting that TLRs could participate in the pathogenesis of PD as promoters of immune/neuroinflammatory responses. Here we will summarize our current understanding on the mechanisms of αSyn aggregation and misfolding, focusing on the contribution of TLRs to the progression of α-synucleinopathies and speculating on their link with the non-motor disturbances associated with aging and neurodegenerative disorders.
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Affiliation(s)
| | - Nadia Ceccato
- Department of Biology, University of Padova, 35131 Padova, Italy
| | - Carmela Conte
- Department of Pharmaceutical Sciences, University of Perugia, 06100 Perugia, Italy
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13
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Schirinzi T, Maftei D, Passali FM, Grillo P, Zenuni H, Mascioli D, Maurizi R, Loccisano L, Vincenzi M, Rinaldi AM, Ralli M, Di Girolamo S, Stefani A, Lattanzi R, Severini C, Mercuri NB. Olfactory Neuron Prokineticin-2 as a Potential Target in Parkinson's Disease. Ann Neurol 2023; 93:196-204. [PMID: 36218142 DOI: 10.1002/ana.26526] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2022] [Revised: 10/05/2022] [Accepted: 10/06/2022] [Indexed: 02/05/2023]
Abstract
OBJECTIVE The objective of this study was to outline the dynamics of prokineticin-2 pathway in relation to clinical-pathological features of Parkinson's disease by examining olfactory neurons of patients. METHODS Thirty-eight patients (26 de novo, newly diagnosed) and 31 sex/age-matched healthy controls underwent noninvasive mucosa brushing for olfactory neurons collection, and standard clinical assessment. Gene expression levels of prokineticin-2, prokineticin-2 receptors type 1 and 2, and prokineticin-2-long peptide were measured in olfactory neurons by real-time polymerase chain reaction (PCR); moreover, the prokineticin-2 protein and α-synuclein species (total and oligomeric) were quantified by immunofluorescence staining. RESULTS Prokineticin-2 expression was significantly increased in Parkinson's disease. De novo patients had higher prokineticin-2 levels, directly correlated with Movement Disorder Society-Sponsored Revision of the Unified Parkinson Disease Rating Scale (MDS-UPDRS) part III motor score. In addition, oligomeric α-synuclein was higher in Parkinson's disease and directly correlated with prokineticin-2 protein levels. Total α-synuclein did not differ between patients and controls. INTERPRETATION Prokineticin-2 is a chemokine showing neuroprotective effects in experimental models of Parkinson's disease, but translational proof of its role in patients is still lacking. Here, we used olfactory neurons as the ideal tissue to analyze molecular stages of neurodegeneration in vivo, providing unprecedented evidence that the prokineticin-2 pathway is activated in patients with Parkinson's disease. Specifically, prokineticin-2 expression in olfactory neurons was higher at early disease stages, proportional to motor severity, and associated with oligomeric α-synuclein accumulation. These data, consistently with preclinical findings, support prokineticin-2 as a candidate target in Parkinson's disease, and validate reliability of olfactory neurons to reflect pathological changes of the disease. ANN NEUROL 2023;93:196-204.
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Affiliation(s)
- Tommaso Schirinzi
- Unit of Neurology, Department of Systems Medicine, Tor Vergata University of Rome, Rome, Italy
| | - Daniela Maftei
- Department of Physiology and Pharmacology "V. Erspamer,", Sapienza University of Rome, Rome, Italy
| | - Francesco M Passali
- Unit of ENT, Department of Clinical Sciences and Translational Medicine, Tor Vergata University of Rome, Rome, Italy
| | - Piergiorgio Grillo
- Unit of Neurology, Department of Systems Medicine, Tor Vergata University of Rome, Rome, Italy
| | - Henri Zenuni
- Unit of Neurology, Department of Systems Medicine, Tor Vergata University of Rome, Rome, Italy
| | - Davide Mascioli
- Unit of Neurology, Department of Systems Medicine, Tor Vergata University of Rome, Rome, Italy
| | - Riccardo Maurizi
- Unit of ENT, Department of Clinical Sciences and Translational Medicine, Tor Vergata University of Rome, Rome, Italy
| | - Laura Loccisano
- Unit of ENT, Department of Clinical Sciences and Translational Medicine, Tor Vergata University of Rome, Rome, Italy
| | - Martina Vincenzi
- Department of Physiology and Pharmacology "V. Erspamer,", Sapienza University of Rome, Rome, Italy
| | - Anna Maria Rinaldi
- Department of Systems Medicine, Tor Vergata University of Rome, Rome, Italy
| | - Massimo Ralli
- Department of Sense Organs, Sapienza University of Rome, Rome, Italy
| | - Stefano Di Girolamo
- Unit of ENT, Department of Clinical Sciences and Translational Medicine, Tor Vergata University of Rome, Rome, Italy
| | - Alessandro Stefani
- Unit of Neurology, Department of Systems Medicine, Tor Vergata University of Rome, Rome, Italy
| | - Roberta Lattanzi
- Department of Physiology and Pharmacology "V. Erspamer,", Sapienza University of Rome, Rome, Italy
| | - Cinzia Severini
- Department of Biochemistry and Cell Biology, National Research Council of Italy, Rome, Italy
| | - Nicola B Mercuri
- Unit of Neurology, Department of Systems Medicine, Tor Vergata University of Rome, Rome, Italy.,European Centre for Brain Research, IRCCS Fondazione Santa Lucia, Rome, Italy
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14
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Neurotoxicity of diesel exhaust extracts in zebrafish and its implications for neurodegenerative disease. Sci Rep 2022; 12:19371. [PMID: 36371460 PMCID: PMC9653411 DOI: 10.1038/s41598-022-23485-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2022] [Accepted: 11/01/2022] [Indexed: 11/13/2022] Open
Abstract
Long-term air pollution (AP) exposure, including diesel exhaust exposure, is increasingly being recognized as a major contributor to the development of neurodegenerative diseases such as Parkinson's and Alzheimer's disease. How AP increases the risk of neurodegeneration is not well understood but might include direct neurotoxicity and CNS inflammation. We investigated the impact of diesel exhaust particulate extract (DEPe) exposure on the brain and the mechanisms by which microglia and astroglia might mediate neuronal changes. Zebrafish (ZF) were utilized to determine neuronal toxicity of and microglial response to DEPe and single cell RNA sequencing was employed to study cell type-specific transcriptomic responses within the ZF brain. DEPe exposure induced neuronal injury and microglial activation in vivo. However, preventing the development of microglia did not attenuate DEPe-induced neuron loss, leading us to investigate microglial, astroglial, and neuronal response to DEPe exposure at single-cell resolution. Differentially expressed genes and disease-relevant pathways were identified within glial and neuronal clusters after DEPe exposure. Microglia and astroglia existed in multiple states, some of which appear toxic and others protective to neurons. Neuronal transcriptomic analysis revealed that DEPe exposure reduced expression of autophagy-related genes consistent with direct neurotoxicity. In summary, DEPe exposure was neurotoxic in developing ZF larvae and induced neuroinflammation. The microglial inflammatory response did not contribute to neurotoxicity of DEPe and in fact, some glial clusters upregulated transcriptional pathways that are likely protective. Furthermore, DEPe exposure led to reduced expression of autophagy-related genes in neurons that likely contribute to its toxicity.
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15
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Molecular and Cellular Interactions in Pathogenesis of Sporadic Parkinson Disease. Int J Mol Sci 2022; 23:ijms232113043. [PMID: 36361826 PMCID: PMC9657547 DOI: 10.3390/ijms232113043] [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: 08/20/2022] [Revised: 10/16/2022] [Accepted: 10/25/2022] [Indexed: 11/23/2022] Open
Abstract
An increasing number of the population all around the world suffer from age-associated neurodegenerative diseases including Parkinson’s disease (PD). This disorder presents different signs of genetic, epigenetic and environmental origin, and molecular, cellular and intracellular dysfunction. At the molecular level, α-synuclein (αSyn) was identified as the principal molecule constituting the Lewy bodies (LB). The gut microbiota participates in the pathogenesis of PD and may contribute to the loss of dopaminergic neurons through mitochondrial dysfunction. The most important pathogenetic link is an imbalance of Ca2+ ions, which is associated with redox imbalance in the cells and increased generation of reactive oxygen species (ROS). In this review, genetic, epigenetic and environmental factors that cause these disorders and their cause-and-effect relationships are considered. As a constituent of environmental factors, the example of organophosphates (OPs) is also reviewed. The role of endothelial damage in the pathogenesis of PD is discussed, and a ‘triple hit hypothesis’ is proposed as a modification of Braak’s dual hit one. In the absence of effective therapies for neurodegenerative diseases, more and more evidence is emerging about the positive impact of nutritional structure and healthy lifestyle on the state of blood vessels and the risk of developing these diseases.
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16
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Chen M, Liu J, Luo H, Duan C, Gao G, Yang H. Increase in membrane surface expression and phosphorylation of TRPC3 related to olfactory dysfunction in α-synuclein transgenic mice. J Cell Mol Med 2022; 26:5008-5020. [PMID: 36029194 PMCID: PMC9549507 DOI: 10.1111/jcmm.17524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Revised: 08/05/2022] [Accepted: 08/10/2022] [Indexed: 11/28/2022] Open
Abstract
Olfactory impairment is an initial non-motor symptom of Parkinson's disease that causes the deposition of aggregated α-synuclein (α-syn) in olfactory neurons. Transient receptor potential canonical (TRPC) channels are a diverse group of non-selective Ca2+ entry channels involved in the progression or pathogenesis of PD via Ca2+ homeostatic regulation. However, the relationship between TRPC and α-syn pathology in an olfactory system remains unclear. To address this issue, we assessed the olfactory function in α-syn transgenic mice. In contrast with control mice, the transgenic mice exhibited impaired olfaction, TRPC3 activation and apoptotic neuronal cell death in the olfactory system. Similar results were observed in primary cultures of olfactory neurons, that is TRPC3 activation, increasing intracellular Ca2+ concentration and apoptotic cell death in the α-syn-overexpressed neurons. These changes were significantly attenuated by TRPC3 knockdown. Therefore, our findings suggest that TRPC3 activation and calcium dyshomeostasis play a key role in α-syn-induced olfactory dysfunction in mice.
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Affiliation(s)
- Min Chen
- Department of Neurobiology School of Basic Medical Sciences, Key Laboratory of Neural Regeneration and Repair, Center for Parkinson's Disease, Key Laboratory for Neurodegenerative Diseases of the Ministry of Education, Beijing Institute for Brain Disorders, Capital Medical University, Beijing, China.,Guangxi Neurological Disease Clinical Research Center, Laboratory of Neuroscience, Affiliated Hospital of Guilin Medical University, Guilin, China
| | - Jia Liu
- Department of Neurobiology School of Basic Medical Sciences, Key Laboratory of Neural Regeneration and Repair, Center for Parkinson's Disease, Key Laboratory for Neurodegenerative Diseases of the Ministry of Education, Beijing Institute for Brain Disorders, Capital Medical University, Beijing, China
| | - Hanjiang Luo
- Guangxi Neurological Disease Clinical Research Center, Laboratory of Neuroscience, Affiliated Hospital of Guilin Medical University, Guilin, China
| | - Chunli Duan
- Department of Neurobiology School of Basic Medical Sciences, Key Laboratory of Neural Regeneration and Repair, Center for Parkinson's Disease, Key Laboratory for Neurodegenerative Diseases of the Ministry of Education, Beijing Institute for Brain Disorders, Capital Medical University, Beijing, China
| | - Ge Gao
- Department of Neurobiology School of Basic Medical Sciences, Key Laboratory of Neural Regeneration and Repair, Center for Parkinson's Disease, Key Laboratory for Neurodegenerative Diseases of the Ministry of Education, Beijing Institute for Brain Disorders, Capital Medical University, Beijing, China
| | - Hui Yang
- Department of Neurobiology School of Basic Medical Sciences, Key Laboratory of Neural Regeneration and Repair, Center for Parkinson's Disease, Key Laboratory for Neurodegenerative Diseases of the Ministry of Education, Beijing Institute for Brain Disorders, Capital Medical University, Beijing, China
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17
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Bongianni M, Catalan M, Perra D, Fontana E, Janes F, Bertolotti C, Sacchetto L, Capaldi S, Tagliapietra M, Polverino P, Tommasini V, Bellavita G, Kachoie EA, Baruca R, Bernardini A, Valente M, Fiorini M, Bronzato E, Tamburin S, Bertolasi L, Brozzetti L, Cecchini MP, Gigli G, Monaco S, Manganotti P, Zanusso G. Olfactory swab sampling optimization for α-synuclein aggregate detection in patients with Parkinson's disease. Transl Neurodegener 2022; 11:37. [PMID: 35902902 PMCID: PMC9330656 DOI: 10.1186/s40035-022-00311-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 07/18/2022] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND In patients with Parkinson's disease (PD), real-time quaking-induced conversion (RT-QuIC) detection of pathological α-synuclein (α-syn) in olfactory mucosa (OM) is not as accurate as in other α-synucleinopathies. It is unknown whether these variable results might be related to a different distribution of pathological α-syn in OM. Thus, we investigated whether nasal swab (NS) performed in areas with a different coverage by olfactory neuroepithelium, such as agger nasi (AN) and middle turbinate (MT), might affect the detection of pathological α-syn. METHODS NS was performed in 66 patients with PD and 29 non-PD between September 2018 and April 2021. In 43 patients, cerebrospinal fluid (CSF) was also obtained and all samples were analyzed by RT-QuIC for α-syn. RESULTS In the first round, 72 OM samples were collected by NS, from AN (NSAN) or from MT (NSMT), and 35 resulted positive for α-syn RT-QuIC, including 27/32 (84%) from AN, 5/11 (45%) from MT, and 3/29 (10%) belonging to the non-PD patients. Furthermore, 23 additional PD patients underwent NS at both AN and MT, and RT-QuIC revealed α-syn positive in 18/23 (78%) NSAN samples and in 10/23 (44%) NSMT samples. Immunocytochemistry of NS preparations showed a higher representation of olfactory neural cells in NSAN compared to NSMT. We also observed α-syn and phospho-α-syn deposits in NS from PD patients but not in controls. Finally, RT-QuIC was positive in 22/24 CSF samples from PD patients (92%) and in 1/19 non-PD. CONCLUSION In PD patients, RT-QuIC sensitivity is significantly increased (from 45% to 84%) when NS is performed at AN, indicating that α-syn aggregates are preferentially detected in olfactory areas with higher concentration of olfactory neurons. Although RT-QuIC analysis of CSF showed a higher diagnostic accuracy compared to NS, due to the non-invasiveness, NS might be considered as an ancillary procedure for PD diagnosis.
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Affiliation(s)
- Matilde Bongianni
- Department of Neurosciences, Biomedicine, and Movement Sciences, Policlinico G. B. Rossi, University of Verona, 37134, Verona, Italy
| | - Mauro Catalan
- Neurology Unit, Department of Medicine, Surgery and Health Sciences, Ospedale Cattinara, University of Trieste, 34128, Trieste, Italy
| | - Daniela Perra
- Department of Neurosciences, Biomedicine, and Movement Sciences, Policlinico G. B. Rossi, University of Verona, 37134, Verona, Italy
| | - Elena Fontana
- Department of Neurosciences, Biomedicine, and Movement Sciences, Policlinico G. B. Rossi, University of Verona, 37134, Verona, Italy
| | - Francesco Janes
- Neurology Unit, University of Udine Academic Hospital, 33100, Udine, Italy
| | - Claudio Bertolotti
- Neurology Unit, Department of Medicine, Surgery and Health Sciences, Ospedale Cattinara, University of Trieste, 34128, Trieste, Italy
| | - Luca Sacchetto
- Department of Surgical Sciences, Dentistry, Gynecology and Pediatrics, University of Verona, 37134, Verona, Italy
| | - Stefano Capaldi
- Biocrystallography Laboratory, Department of Biotechnology, University of Verona, 37134, Verona, Italy
| | - Matteo Tagliapietra
- Department of Neurosciences, Biomedicine, and Movement Sciences, Policlinico G. B. Rossi, University of Verona, 37134, Verona, Italy
| | - Paola Polverino
- Neurology Unit, Department of Medicine, Surgery and Health Sciences, Ospedale Cattinara, University of Trieste, 34128, Trieste, Italy
| | - Valentina Tommasini
- Neurology Unit, Department of Medicine, Surgery and Health Sciences, Ospedale Cattinara, University of Trieste, 34128, Trieste, Italy
| | - Giulia Bellavita
- Neurology Unit, Department of Medicine, Surgery and Health Sciences, Ospedale Cattinara, University of Trieste, 34128, Trieste, Italy
| | - Elham Ataie Kachoie
- Biocrystallography Laboratory, Department of Biotechnology, University of Verona, 37134, Verona, Italy
| | - Roberto Baruca
- Otolaryngology Unit, Department of Medicine, Surgery and Health Sciences, Ospedale Cattinara, University of Trieste, 34128, Trieste, Italy
| | - Andrea Bernardini
- Neurology Unit, University of Udine Academic Hospital, 33100, Udine, Italy
| | | | - Michele Fiorini
- Department of Neurosciences, Biomedicine, and Movement Sciences, Policlinico G. B. Rossi, University of Verona, 37134, Verona, Italy
| | - Erika Bronzato
- Department of Neurosciences, Biomedicine, and Movement Sciences, Policlinico G. B. Rossi, University of Verona, 37134, Verona, Italy
| | - Stefano Tamburin
- Department of Neurosciences, Biomedicine, and Movement Sciences, Policlinico G. B. Rossi, University of Verona, 37134, Verona, Italy
| | - Laura Bertolasi
- Department of Neurosciences, Biomedicine, and Movement Sciences, Policlinico G. B. Rossi, University of Verona, 37134, Verona, Italy
| | - Lorenzo Brozzetti
- Department of Neurosciences, Biomedicine, and Movement Sciences, Policlinico G. B. Rossi, University of Verona, 37134, Verona, Italy
| | - Maria Paola Cecchini
- Department of Neurosciences, Biomedicine, and Movement Sciences, Policlinico G. B. Rossi, University of Verona, 37134, Verona, Italy
| | - Gianluigi Gigli
- Neurology Unit, University of Udine Academic Hospital, 33100, Udine, Italy
| | - Salvatore Monaco
- Department of Neurosciences, Biomedicine, and Movement Sciences, Policlinico G. B. Rossi, University of Verona, 37134, Verona, Italy
| | - Paolo Manganotti
- Neurology Unit, Department of Medicine, Surgery and Health Sciences, Ospedale Cattinara, University of Trieste, 34128, Trieste, Italy
| | - Gianluigi Zanusso
- Department of Neurosciences, Biomedicine, and Movement Sciences, Policlinico G. B. Rossi, University of Verona, 37134, Verona, Italy.
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18
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Villar-Conde S, Astillero-Lopez V, Gonzalez-Rodriguez M, Saiz-Sanchez D, Ubeda-Banon I, Flores-Cuadrado A, Martinez-Marcos A. Neuronal and glial characterization in the rostrocaudal axis of the human anterior olfactory nucleus: Involvement in Parkinson’s disease. Front Neuroanat 2022; 16:907373. [PMID: 35923614 PMCID: PMC9339613 DOI: 10.3389/fnana.2022.907373] [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: 03/29/2022] [Accepted: 06/27/2022] [Indexed: 12/02/2022] Open
Abstract
Hyposmia is one of the prodromal symptoms of Parkinson’s disease (PD) and a red flag in clinical diagnosis. Neuropathologically, this sign correlates with α-synuclein involvement in the anterior olfactory nucleus (AON). Neurodegeneration, microgliosis, and astrogliosis in AON are poorly studied, and bulbar AON is the focus of these studies with contradictory results. Additionally, male sex is a risk marker for developing PD, but sexual dimorphism of neural and glial populations in the AON has rarely been considered. The aim of this study was to analyze the density of NeuN, Iba-1, GFAP, and Lewy bodies (LBs), as well as the relationship of these cell type markers with pathology along the rostrocaudal axis of the AON (bulbar, retrobulbar, cortical anterior, and posterior divisions). Cavalieri, optical fractionator, and area fraction fractionator stereological approaches were used for the volume, cell populations and LBs densities, area fraction, and percentage of overlap. Iba-1 and α-syn intensities were measured using ImageJ. In non-PD (NPD) cases, the volume was lower in the AON at the extremes of the rostrocaudal axis than in the intermediate divisions. Cortical anterior AON volume decreased in PD compared with NPD cases. NeuN density decreased rostrocaudally in AON portions in NPD and PD cases. This occurred similarly in Iba-1 but only in PD samples. Iba-1 intensity significantly increased in bulbar AON between PD and NPD. No changes were found in astrocytes. Eight percent of NeuN, 0.1% of Iba-1, and 0.1% of GFAP areas overlapped with LBs area along the AON portions. The data indicate that bulbar AON, which is the most rostral portion in this axis, could play a major role in the pathology. This could be related to the larger area occupied by LBs in these divisions.
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19
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Murray HC, Johnson K, Sedlock A, Highet B, Dieriks BV, Anekal PV, Faull RLM, Curtis MA, Koretsky A, Maric D. Lamina-specific immunohistochemical signatures in the olfactory bulb of healthy, Alzheimer's and Parkinson's disease patients. Commun Biol 2022; 5:88. [PMID: 35075270 PMCID: PMC8786934 DOI: 10.1038/s42003-022-03032-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Accepted: 12/27/2021] [Indexed: 12/17/2022] Open
Abstract
Traditional neuroanatomy immunohistology studies involve low-content analyses of a few antibodies of interest, typically applied and compared across sequential tissue sections. The efficiency, consistency, and ultimate insights of these studies can be substantially improved using high-plex immunofluorescence labelling on a single tissue section to allow direct comparison of many markers. Here we present an expanded and efficient multiplexed fluorescence-based immunohistochemistry (MP-IHC) approach that improves throughput with sequential labelling of up to 10 antibodies per cycle, with no limitation on the number of cycles, and maintains versatility and accessibility by using readily available commercial reagents and standard epifluorescence microscopy imaging. We demonstrate this approach by cumulatively screening up to 100 markers on formalin-fixed paraffin-embedded sections of human olfactory bulb sourced from neurologically normal (no significant pathology), Alzheimer's (AD), and Parkinson's disease (PD) patients. This brain region is involved early in the symptomology and pathophysiology of AD and PD. We also developed a spatial pixel bin analysis approach for unsupervised analysis of the high-content anatomical information from large tissue sections. Here, we present a comprehensive immunohistological characterisation of human olfactory bulb anatomy and a summary of differentially expressed biomarkers in AD and PD using the MP-IHC labelling and spatial protein analysis pipeline.
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Affiliation(s)
- Helen C Murray
- Department of Anatomy and Medical Imaging and Centre for Brain Research, Faculty of Medical and Health Science, University of Auckland, Private Bag, Auckland, 92019, New Zealand.
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, 20892, USA.
| | - Kory Johnson
- Bioinformatics Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Andrea Sedlock
- Flow and Imaging Cytometry Core Facility, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Blake Highet
- Department of Anatomy and Medical Imaging and Centre for Brain Research, Faculty of Medical and Health Science, University of Auckland, Private Bag, Auckland, 92019, New Zealand
| | - Birger Victor Dieriks
- Department of Anatomy and Medical Imaging and Centre for Brain Research, Faculty of Medical and Health Science, University of Auckland, Private Bag, Auckland, 92019, New Zealand
| | - Praju Vikas Anekal
- Department of Anatomy and Medical Imaging and Centre for Brain Research, Faculty of Medical and Health Science, University of Auckland, Private Bag, Auckland, 92019, New Zealand
- Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA, 02115, USA
| | - Richard L M Faull
- Department of Anatomy and Medical Imaging and Centre for Brain Research, Faculty of Medical and Health Science, University of Auckland, Private Bag, Auckland, 92019, New Zealand
| | - Maurice A Curtis
- Department of Anatomy and Medical Imaging and Centre for Brain Research, Faculty of Medical and Health Science, University of Auckland, Private Bag, Auckland, 92019, New Zealand
| | - Alan Koretsky
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Dragan Maric
- Flow and Imaging Cytometry Core Facility, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, 20892, USA.
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20
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Wang C, Yang T, Liang M, Xie J, Song N. Astrocyte dysfunction in Parkinson's disease: from the perspectives of transmitted α-synuclein and genetic modulation. Transl Neurodegener 2021; 10:39. [PMID: 34657636 PMCID: PMC8522040 DOI: 10.1186/s40035-021-00265-y] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 10/05/2021] [Indexed: 01/20/2023] Open
Abstract
Parkinson's disease (PD) is a common neurodegenerative disorder that primarily affects the elderly. While the etiology of PD is likely multifactorial with the involvement of genetic, environmental, aging and other factors, α-synuclein (α-syn) pathology is a pivotal mechanism underlying the development of PD. In recent years, astrocytes have attracted considerable attention in the field. Although astrocytes perform a variety of physiological functions in the brain, they are pivotal mediators of α-syn toxicity since they internalize α-syn released from damaged neurons, and this triggers an inflammatory response, protein degradation dysfunction, mitochondrial dysfunction and endoplasmic reticulum stress. Astrocytes are indispensable coordinators in the background of several genetic mutations, including PARK7, GBA1, LRRK2, ATP13A2, PINK1, PRKN and PLA2G6. As the most abundant glial cells in the brain, functional astrocytes can be replenished and even converted to functional neurons. In this review, we discuss astrocyte dysfunction in PD with an emphasis on α-syn toxicity and genetic modulation and conclude that astrocyte replenishment is a valuable therapeutic approach in PD.
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Affiliation(s)
- Changjing Wang
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders, School of Basic Medicine, Qingdao University, Qingdao, 266071, China
| | - Tongtong Yang
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders, School of Basic Medicine, Qingdao University, Qingdao, 266071, China
| | - Meiyu Liang
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders, School of Basic Medicine, Qingdao University, Qingdao, 266071, China
| | - Junxia Xie
- Institute of Brain Science and Disease, Qingdao University, Qingdao, 266071, China.
| | - Ning Song
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders, School of Basic Medicine, Qingdao University, Qingdao, 266071, China.
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21
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Sevgi F, Brauchle EM, Carvajal Berrio DA, Schenke-Layland K, Casadei N, Salker MS, Riess O, Singh Y. Imaging of α-Synuclein Aggregates in a Rat Model of Parkinson's Disease Using Raman Microspectroscopy. Front Cell Dev Biol 2021; 9:664365. [PMID: 34568310 PMCID: PMC8461246 DOI: 10.3389/fcell.2021.664365] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 06/14/2021] [Indexed: 11/18/2022] Open
Abstract
A hallmark of Parkinson’s disease (PD) is the formation of Lewy bodies in the brain. Lewy bodies are rich in the aggregated form of misfolded α-Synuclein (α-Syn). The brain from PD patients can only be analyzed after postmortem, therefore, limiting the diagnosis of PD to the manifestation of motor symptoms. In PD patients and animal models, phosphorylated α-Syn was detected in the peripheral tissues including the gut, thus, raising the hypothesis that early-stage PD could be diagnosed based on colon tissue biopsies. Non-invasive marker-free technologies represent ideal methods to potentially detect aggregated α-Syn in vivo. Raman microspectroscopy has been established for the detection of molecular changes such as alterations of protein structures. Using Raman imaging and microspectroscopy, we analyzed the olfactory bulb in the brain and the muscularis mucosae of colon tissue sections of a human BAC-SNCA transgenic (TG) rat model. Raman images from TG and WT rats were investigated using principal component analysis (PCA) and true component analysis (TCA). Spectral components indicated protein aggregates (spheroidal oligomers) in the TG rat brain and in the colon tissues even at a young age but not in WT. In summary, we have demonstrated that Raman imaging is capable of detecting α-Syn aggregates in colon tissues of a PD rat model and making it a promising tool for future use in PD pathology.
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Affiliation(s)
- Fide Sevgi
- Department of Women's Health, Research Institute for Women's Health, Eberhard Karls Tübingen University, Tübingen, Germany
| | - Eva M Brauchle
- Department of Women's Health, Research Institute for Women's Health, Eberhard Karls Tübingen University, Tübingen, Germany.,Natural and Medical Sciences Institute (NMI), Tübingen University, Reutlingen, Germany.,Cluster of Excellence iFIT (EXC 2180) "Image-Guided and Functionally Instructed Tumor Therapies", Eberhard Karls University Tübingen, Tübingen, Germany
| | - Daniel A Carvajal Berrio
- Department of Women's Health, Research Institute for Women's Health, Eberhard Karls Tübingen University, Tübingen, Germany.,Cluster of Excellence iFIT (EXC 2180) "Image-Guided and Functionally Instructed Tumor Therapies", Eberhard Karls University Tübingen, Tübingen, Germany
| | - Katja Schenke-Layland
- Department of Women's Health, Research Institute for Women's Health, Eberhard Karls Tübingen University, Tübingen, Germany.,Natural and Medical Sciences Institute (NMI), Tübingen University, Reutlingen, Germany.,Cluster of Excellence iFIT (EXC 2180) "Image-Guided and Functionally Instructed Tumor Therapies", Eberhard Karls University Tübingen, Tübingen, Germany.,Department of Medicine/Cardiology, Cardiovascular Research Laboratories, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States
| | - Nicolas Casadei
- Institute of Medical Genetics and Applied Genomics, Eberhard Karls Tübingen University, Tübingen, Germany
| | - Madhuri S Salker
- Department of Women's Health, Research Institute for Women's Health, Eberhard Karls Tübingen University, Tübingen, Germany
| | - Olaf Riess
- Institute of Medical Genetics and Applied Genomics, Eberhard Karls Tübingen University, Tübingen, Germany
| | - Yogesh Singh
- Department of Women's Health, Research Institute for Women's Health, Eberhard Karls Tübingen University, Tübingen, Germany.,Institute of Medical Genetics and Applied Genomics, Eberhard Karls Tübingen University, Tübingen, Germany
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22
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Increased YKL-40 but Not C-Reactive Protein Levels in Patients with Alzheimer's Disease. Biomedicines 2021; 9:biomedicines9091094. [PMID: 34572280 PMCID: PMC8467854 DOI: 10.3390/biomedicines9091094] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 08/16/2021] [Accepted: 08/23/2021] [Indexed: 11/17/2022] Open
Abstract
Neuroinflammation is a common feature in Alzheimer’s (AD) and Parkinson’s (PD) disease. In the last few decades, a testable hypothesis was proposed that protein-unfolding events might occur due to neuroinflammatory cascades involving alterations in the crosstalk between glial cells and neurons. Here, we tried to clarify the pattern of two of the most promising biomarkers of neuroinflammation in cerebrospinal fluid (CSF) in AD and PD. This study included cognitively unimpaired elderly patients, patients with mild cognitive impairment, patients with AD dementia, and patients with PD. CSF samples were analyzed for YKL-40 and C-reactive protein (CRP). We found that CSF YKL-40 levels were significantly increased only in dementia stages of AD. Additionally, increased YKL-40 levels were found in the cerebral orbitofrontal cortex from AD patients in agreement with augmented astrogliosis. Our study confirms that these biomarkers of neuroinflammation are differently detected in CSF from AD and PD patients.
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23
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The Impact of SNCA Variations and Its Product Alpha-Synuclein on Non-Motor Features of Parkinson's Disease. Life (Basel) 2021; 11:life11080804. [PMID: 34440548 PMCID: PMC8401994 DOI: 10.3390/life11080804] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 08/04/2021] [Accepted: 08/06/2021] [Indexed: 12/14/2022] Open
Abstract
Parkinson’s disease (PD) is a common and progressive neurodegenerative disease, caused by the loss of dopaminergic neurons in the substantia nigra pars compacta in the midbrain, which is clinically characterized by a constellation of motor and non-motor manifestations. The latter include hyposmia, constipation, depression, pain and, in later stages, cognitive decline and dysautonomia. The main pathological features of PD are neuronal loss and consequent accumulation of Lewy bodies (LB) in the surviving neurons. Alpha-synuclein (α-syn) is the main component of LB, and α-syn aggregation and accumulation perpetuate neuronal degeneration. Mutations in the α-syn gene (SNCA) were the first genetic cause of PD to be identified. Generally, patients carrying SNCA mutations present early-onset parkinsonism with severe and early non-motor symptoms, including cognitive decline. Several SNCA polymorphisms were also identified, and some of them showed association with non-motor manifestations. The functional role of these polymorphisms is only partially understood. In this review we explore the contribution of SNCA and its product, α-syn, in predisposing to the non-motor manifestations of PD.
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24
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Affiliation(s)
- E Ray Dorsey
- Center for Health + Technology, Department of Neurology, University of Rochester Medical Center, Rochester, New York
| | - Michael S Okun
- Norman Fixel Institute for Neurological Diseases, Department of Neurology, University of Florida, Gainesville.,Associate Editor, JAMA Neurology
| | - Caroline M Tanner
- Weill Institute for Neurosciences, Department of Neurology, University of California, San Francisco
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25
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The Olfactory System as Marker of Neurodegeneration in Aging, Neurological and Neuropsychiatric Disorders. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:ijerph18136976. [PMID: 34209997 PMCID: PMC8297221 DOI: 10.3390/ijerph18136976] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 06/19/2021] [Accepted: 06/24/2021] [Indexed: 12/14/2022]
Abstract
Research studies that focus on understanding the onset of neurodegenerative pathology and therapeutic interventions to inhibit its causative factors, have shown a crucial role of olfactory bulb neurons as they transmit and propagate nerve impulses to higher cortical and limbic structures. In rodent models, removal of the olfactory bulb results in pathology of the frontal cortex that shows striking similarity with frontal cortex features of patients diagnosed with neurodegenerative disorders. Widely different approaches involving behavioral symptom analysis, histopathological and molecular alterations, genetic and environmental influences, along with age-related alterations in cellular pathways, indicate a strong correlation of olfactory dysfunction and neurodegeneration. Indeed, declining olfactory acuity and olfactory deficits emerge either as the very first symptoms or as prodromal symptoms of progressing neurodegeneration of classical conditions. Olfactory dysfunction has been associated with most neurodegenerative, neuropsychiatric, and communication disorders. Evidence revealing the dual molecular function of the olfactory receptor neurons at dendritic and axonal ends indicates the significance of olfactory processing pathways that come under environmental pressure right from the onset. Here, we review findings that olfactory bulb neuronal processing serves as a marker of neuropsychiatric and neurodegenerative disorders.
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26
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Li D, McIntosh CS, Mastaglia FL, Wilton SD, Aung-Htut MT. Neurodegenerative diseases: a hotbed for splicing defects and the potential therapies. Transl Neurodegener 2021; 10:16. [PMID: 34016162 PMCID: PMC8136212 DOI: 10.1186/s40035-021-00240-7] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 04/23/2021] [Indexed: 12/14/2022] Open
Abstract
Precursor messenger RNA (pre-mRNA) splicing is a fundamental step in eukaryotic gene expression that systematically removes non-coding regions (introns) and ligates coding regions (exons) into a continuous message (mature mRNA). This process is highly regulated and can be highly flexible through a process known as alternative splicing, which allows for several transcripts to arise from a single gene, thereby greatly increasing genetic plasticity and the diversity of proteome. Alternative splicing is particularly prevalent in neuronal cells, where the splicing patterns are continuously changing to maintain cellular homeostasis and promote neurogenesis, migration and synaptic function. The continuous changes in splicing patterns and a high demand on many cis- and trans-splicing factors contribute to the susceptibility of neuronal tissues to splicing defects. The resultant neurodegenerative diseases are a large group of disorders defined by a gradual loss of neurons and a progressive impairment in neuronal function. Several of the most common neurodegenerative diseases involve some form of splicing defect(s), such as Alzheimer's disease, Parkinson's disease and spinal muscular atrophy. Our growing understanding of RNA splicing has led to the explosion of research in the field of splice-switching antisense oligonucleotide therapeutics. Here we review our current understanding of the effects alternative splicing has on neuronal differentiation, neuronal migration, synaptic maturation and regulation, as well as the impact on neurodegenerative diseases. We will also review the current landscape of splice-switching antisense oligonucleotides as a therapeutic strategy for a number of common neurodegenerative disorders.
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Affiliation(s)
- Dunhui Li
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Perth, Western Australia, Australia.,Perron Institute for Neurological and Translational Science, Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Perth, Western Australia, Australia
| | - Craig Stewart McIntosh
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Perth, Western Australia, Australia.,Perron Institute for Neurological and Translational Science, Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Perth, Western Australia, Australia
| | - Frank Louis Mastaglia
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Perth, Western Australia, Australia.,Perron Institute for Neurological and Translational Science, Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Perth, Western Australia, Australia
| | - Steve Donald Wilton
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Perth, Western Australia, Australia.,Perron Institute for Neurological and Translational Science, Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Perth, Western Australia, Australia
| | - May Thandar Aung-Htut
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Perth, Western Australia, Australia. .,Perron Institute for Neurological and Translational Science, Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Perth, Western Australia, Australia.
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27
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Cheslow L, Snook AE, Waldman SA. Emerging targets for the diagnosis of Parkinson's disease: examination of systemic biomarkers. Biomark Med 2021; 15:597-608. [PMID: 33988462 DOI: 10.2217/bmm-2020-0654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Parkinson's disease (PD) is a highly prevalent and irreversible neurodegenerative disorder that is typically diagnosed in an advanced stage. Currently, there are no approved biomarkers that reliably identify PD patients before they have undergone extensive neuronal damage, eliminating the opportunity for future disease-modifying therapies to intervene in disease progression. This unmet need for diagnostic and therapeutic biomarkers has fueled PD research for decades, but these efforts have not yet yielded actionable results. Recently, studies exploring mechanisms underlying PD progression have offered insights into multisystemic contributions to pathology, challenging the classic perspective of PD as a disease isolated to the brain. This shift in understanding has opened the door to potential new biomarkers from multiple sites in the body. This review focuses on emerging candidates for PD biomarkers in the context of current diagnostic approaches and multiple organ systems that contribute to disease.
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Affiliation(s)
- Lara Cheslow
- Department of Pharmacology & Experimental Therapeutics, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Adam E Snook
- Department of Pharmacology & Experimental Therapeutics, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Scott A Waldman
- Department of Pharmacology & Experimental Therapeutics, Thomas Jefferson University, Philadelphia, PA 19107, USA
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28
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Neurons and Glia Interplay in α-Synucleinopathies. Int J Mol Sci 2021; 22:ijms22094994. [PMID: 34066733 PMCID: PMC8125822 DOI: 10.3390/ijms22094994] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 04/29/2021] [Accepted: 05/04/2021] [Indexed: 11/16/2022] Open
Abstract
Accumulation of the neuronal presynaptic protein alpha-synuclein within proteinaceous inclusions represents the key histophathological hallmark of a spectrum of neurodegenerative disorders, referred to by the umbrella term a-synucleinopathies. Even though alpha-synuclein is expressed predominantly in neurons, pathological aggregates of the protein are also found in the glial cells of the brain. In Parkinson's disease and dementia with Lewy bodies, alpha-synuclein accumulates mainly in neurons forming the Lewy bodies and Lewy neurites, whereas in multiple system atrophy, the protein aggregates mostly in the glial cytoplasmic inclusions within oligodendrocytes. In addition, astrogliosis and microgliosis are found in the synucleinopathy brains, whereas both astrocytes and microglia internalize alpha-synuclein and contribute to the spread of pathology. The mechanisms underlying the pathological accumulation of alpha-synuclein in glial cells that under physiological conditions express low to non-detectable levels of the protein are an area of intense research. Undoubtedly, the presence of aggregated alpha-synuclein can disrupt glial function in general and can contribute to neurodegeneration through numerous pathways. Herein, we summarize the current knowledge on the role of alpha-synuclein in both neurons and glia, highlighting the contribution of the neuron-glia connectome in the disease initiation and progression, which may represent potential therapeutic target for a-synucleinopathies.
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29
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Bogale TA, Faustini G, Longhena F, Mitola S, Pizzi M, Bellucci A. Alpha-Synuclein in the Regulation of Brain Endothelial and Perivascular Cells: Gaps and Future Perspectives. Front Immunol 2021; 12:611761. [PMID: 33679750 PMCID: PMC7933041 DOI: 10.3389/fimmu.2021.611761] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 01/27/2021] [Indexed: 12/27/2022] Open
Abstract
Misfolded proteins, inflammation, and vascular alterations are common pathological hallmarks of neurodegenerative diseases. Alpha-synuclein is a small synaptic protein that was identified as a major component of Lewy bodies and Lewy neurites in the brain of patients affected by Parkinson's disease (PD), Lewy body dementia (LBD), and other synucleinopathies. It is mainly involved in the regulation of synaptic vesicle trafficking but can also control mitochondrial/endoplasmic reticulum (ER) homeostasis, lysosome/phagosome function, and cytoskeleton organization. Recent evidence supports that the pathological forms of α-synuclein can also reduce the release of vasoactive and inflammatory mediators from endothelial cells (ECs) and modulates the expression of tight junction (TJ) proteins important for maintaining the blood-brain barrier (BBB). This hints that α-synuclein deposition can affect BBB integrity. Border associated macrophages (BAMs) are brain resident macrophages found in association with the vasculature (PVMs), meninges (MAMs), and choroid plexus (CPMs). Recent findings indicate that these cells play distinct roles in stroke and neurodegenerative disorders. Although many studies have addressed how α-synuclein may modulate microglia, its effect on BAMs has been scarcely investigated. This review aims at summarizing the main findings supporting how α-synuclein can affect ECs and/or BAMs function as well as their interplay and effect on other cells in the brain perivascular environment in physiological and pathological conditions. Gaps of knowledge and new perspectives on how this protein can contribute to neurodegeneration by inducing BBB homeostatic changes in different neurological conditions are highlighted.
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Affiliation(s)
- Tizibt Ashine Bogale
- Division of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
| | - Gaia Faustini
- Division of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
| | - Francesca Longhena
- Division of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
| | - Stefania Mitola
- Biotechnology Division, Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
- Laboratory for Preventive and Personalized Medicine, Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
| | - Marina Pizzi
- Division of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
| | - Arianna Bellucci
- Division of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
- Laboratory for Preventive and Personalized Medicine, Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
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30
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Flores-Cuadrado A, Saiz-Sanchez D, Mohedano-Moriano A, Lamas-Cenjor E, Leon-Olmo V, Martinez-Marcos A, Ubeda-Bañon I. Astrogliosis and sexually dimorphic neurodegeneration and microgliosis in the olfactory bulb in Parkinson's disease. NPJ PARKINSONS DISEASE 2021; 7:11. [PMID: 33479244 PMCID: PMC7820595 DOI: 10.1038/s41531-020-00154-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 12/01/2020] [Indexed: 02/07/2023]
Abstract
Hyposmia is prodromal, and male sex is a risk marker for an enhanced likelihood ratio of Parkinson’s disease. The literature regarding olfactory bulb volume reduction is controversial, although the olfactory bulb has been largely reported as an early and preferential site for α-synucleinopathy. These pathological deposits have been correlated with neural loss in Nissl-stained material. However, microgliosis has rarely been studied, and astrogliosis has been virtually neglected. In the present report, α-synucleinopathy (α-synuclein), neurodegeneration (Neu-N), astrogliosis (GFAP), and microgliosis (Iba-1) were quantified, using specific markers and stereological methods. Disease, sex, age, disease duration, and post-mortem interval were considered variables for statistical analysis. No volumetric changes have been identified regarding disease or sex. α-Synucleinopathy was present throughout the OB, mainly concentrated on anterior olfactory nucleus. Neurodegeneration (reduction in Neu-N-positive cells) was statistically significant in the diseased group. Astrogliosis (increased GFAP labeling) and microgliosis (increased Iba-1 labeling) were significantly enhanced in the Parkinson’s disease group. When analyzed per sex, neurodegeneration and microgliosis differences are only present in men. These data constitute the demonstration of sex differences in neurodegeneration using specific neural markers, enhanced astrogliosis and increased microgliosis, also linked to male sex, in the human olfactory bulb in Parkinson’s disease.
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Affiliation(s)
- Alicia Flores-Cuadrado
- Neuroplasticity & Neurodegeneration Laboratory, Ciudad Real Medical School, CRIB, University of Castilla-La Mancha, 13071, Ciudad Real, Spain
| | - Daniel Saiz-Sanchez
- Neuroplasticity & Neurodegeneration Laboratory, Ciudad Real Medical School, CRIB, University of Castilla-La Mancha, 13071, Ciudad Real, Spain
| | - Alicia Mohedano-Moriano
- Faculty of Health Sciences, University of Castilla-La Mancha, 45600, Talavera de la Reina, Spain
| | - Elena Lamas-Cenjor
- Neuroplasticity & Neurodegeneration Laboratory, Ciudad Real Medical School, CRIB, University of Castilla-La Mancha, 13071, Ciudad Real, Spain
| | - Victor Leon-Olmo
- Neuroplasticity & Neurodegeneration Laboratory, Ciudad Real Medical School, CRIB, University of Castilla-La Mancha, 13071, Ciudad Real, Spain
| | - Alino Martinez-Marcos
- Neuroplasticity & Neurodegeneration Laboratory, Ciudad Real Medical School, CRIB, University of Castilla-La Mancha, 13071, Ciudad Real, Spain
| | - Isabel Ubeda-Bañon
- Neuroplasticity & Neurodegeneration Laboratory, Ciudad Real Medical School, CRIB, University of Castilla-La Mancha, 13071, Ciudad Real, Spain.
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31
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New Insights into Immune-Mediated Mechanisms in Parkinson's Disease. Int J Mol Sci 2020; 21:ijms21239302. [PMID: 33291304 PMCID: PMC7730912 DOI: 10.3390/ijms21239302] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Revised: 12/03/2020] [Accepted: 12/03/2020] [Indexed: 02/06/2023] Open
Abstract
The immune system has been increasingly recognized as a major contributor in the pathogenesis of Parkinson’s disease (PD). The double-edged nature of the immune system poses a problem in harnessing immunomodulatory therapies to prevent and slow the progression of this debilitating disease. To tackle this conundrum, understanding the mechanisms underlying immune-mediated neuronal death will aid in the identification of neuroprotective strategies to preserve dopaminergic neurons. Specific innate and adaptive immune mediators may directly or indirectly induce dopaminergic neuronal death. Genetic factors, the gut-brain axis and the recent identification of PD-specific T cells may provide novel mechanistic insights on PD pathogenesis. Future studies to address the gaps in the identification of autoantibodies, variability in immunophenotyping studies and the contribution of gut dysbiosis to PD may eventually provide new therapeutic targets for PD.
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32
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Highet B, Dieriks BV, Murray HC, Faull RLM, Curtis MA. Huntingtin Aggregates in the Olfactory Bulb in Huntington's Disease. Front Aging Neurosci 2020; 12:261. [PMID: 33013352 PMCID: PMC7461834 DOI: 10.3389/fnagi.2020.00261] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 07/31/2020] [Indexed: 12/03/2022] Open
Abstract
Olfactory deficits are an early and prevalent non-motor symptom of Huntington's disease (HD). In other neurodegenerative diseases where olfactory deficits occur, such as Alzheimer's disease and Parkinson's disease, pathological protein aggregates (tau, β-amyloid, α-synuclein) accumulate in the anterior olfactory nucleus (AON) of the olfactory bulb (OFB). Therefore, in this study we determined whether aggregates are also present in HD OFBs; 13 HD and five normal human OFBs were stained for mutant huntingtin (mHtt), tau, β-amyloid, TDP-43, and α-synuclein. Our results show that mHtt aggregates detected with 1F8 antibody are present within all HD OFBs, and mHtt aggregate load in the OFB does not correlate with Vonsattel grading scores. The majority of the aggregates were located in the AON and in similar abundance in each anatomical segment of the AON. No mHtt aggregates were found in controls; 31% of HD cases also contained tau neurofibrillary tangles within the AON. This work demonstrates HD pathology in the OFB and indicates that disease-specific protein aggregation in the AON is a common feature of neurodegenerative diseases that show olfactory deficits.
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Affiliation(s)
- Blake Highet
- Department of Anatomy and Medical Imaging, Faculty of Medical and Health Science, The University of Auckland, Auckland, New Zealand
- Centre for Brain Research, Faculty of Medical and Health Science, The University of Auckland, Auckland, New Zealand
| | - Birger Victor Dieriks
- Department of Anatomy and Medical Imaging, Faculty of Medical and Health Science, The University of Auckland, Auckland, New Zealand
- Centre for Brain Research, Faculty of Medical and Health Science, The University of Auckland, Auckland, New Zealand
| | - Helen C. Murray
- Department of Anatomy and Medical Imaging, Faculty of Medical and Health Science, The University of Auckland, Auckland, New Zealand
- Centre for Brain Research, Faculty of Medical and Health Science, The University of Auckland, Auckland, New Zealand
| | - Richard L. M. Faull
- Department of Anatomy and Medical Imaging, Faculty of Medical and Health Science, The University of Auckland, Auckland, New Zealand
- Centre for Brain Research, Faculty of Medical and Health Science, The University of Auckland, Auckland, New Zealand
| | - Maurice A. Curtis
- Department of Anatomy and Medical Imaging, Faculty of Medical and Health Science, The University of Auckland, Auckland, New Zealand
- Centre for Brain Research, Faculty of Medical and Health Science, The University of Auckland, Auckland, New Zealand
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Tanriöver G, Bacioglu M, Schweighauser M, Mahler J, Wegenast-Braun BM, Skodras A, Obermüller U, Barth M, Kronenberg-Versteeg D, Nilsson KPR, Shimshek DR, Kahle PJ, Eisele YS, Jucker M. Prominent microglial inclusions in transgenic mouse models of α-synucleinopathy that are distinct from neuronal lesions. Acta Neuropathol Commun 2020; 8:133. [PMID: 32787922 PMCID: PMC7425556 DOI: 10.1186/s40478-020-00993-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 07/09/2020] [Indexed: 11/29/2023] Open
Abstract
Alpha-synucleinopathies are a group of progressive neurodegenerative disorders, characterized by intracellular deposits of aggregated α-synuclein (αS). The clinical heterogeneity of these diseases is thought to be attributed to conformers (or strains) of αS but the contribution of inclusions in various cell types is unclear. The aim of the present work was to study αS conformers among different transgenic (TG) mouse models of α-synucleinopathies. To this end, four different TG mouse models were studied (Prnp-h[A53T]αS; Thy1-h[A53T]αS; Thy1-h[A30P]αS; Thy1-mαS) that overexpress human or murine αS and differed in their age-of-symptom onset and subsequent disease progression. Postmortem analysis of end-stage brains revealed robust neuronal αS pathology as evidenced by accumulation of αS serine 129 (p-αS) phosphorylation in the brainstem of all four TG mouse lines. Overall appearance of the pathology was similar and only modest differences were observed among additionally affected brain regions. To study αS conformers in these mice, we used pentameric formyl thiophene acetic acid (pFTAA), a fluorescent dye with amyloid conformation-dependent spectral properties. Unexpectedly, besides the neuronal αS pathology, we also found abundant pFTAA-positive inclusions in microglia of all four TG mouse lines. These microglial inclusions were also positive for Thioflavin S and showed immunoreactivity with antibodies recognizing the N-terminus of αS, but were largely p-αS-negative. In all four lines, spectral pFTAA analysis revealed conformational differences between microglia and neuronal inclusions but not among the different mouse models. Concomitant with neuronal lesions, microglial inclusions were already present at presymptomatic stages and could also be induced by seeded αS aggregation. Although nature and significance of microglial inclusions for human α-synucleinopathies remain to be clarified, the previously overlooked abundance of microglial inclusions in TG mouse models of α-synucleinopathy bears importance for mechanistic and preclinical-translational studies.
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Murray HC, Dieriks BV, Swanson MEV, Anekal PV, Turner C, Faull RLM, Belluscio L, Koretsky A, Curtis MA. The unfolded protein response is activated in the olfactory system in Alzheimer's disease. Acta Neuropathol Commun 2020; 8:109. [PMID: 32665027 PMCID: PMC7362534 DOI: 10.1186/s40478-020-00986-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 07/03/2020] [Indexed: 01/04/2023] Open
Abstract
Olfactory dysfunction is an early and prevalent symptom of Alzheimer’s disease (AD) and the olfactory bulb is a nexus of beta-amyloid plaque and tau neurofibrillary tangle (NFT) pathology during early AD progression. To mitigate the accumulation of misfolded proteins, an endoplasmic reticulum stress response called the unfolded protein response (UPR) occurs in the AD hippocampus. However, chronic UPR activation can lead to apoptosis and the upregulation of beta-amyloid and tau production. Therefore, UPR activation in the olfactory system could be one of the first changes in AD. In this study, we investigated whether two proteins that signal UPR activation are expressed in the olfactory system of AD cases with low or high amounts of aggregate pathology. We used immunohistochemistry to label two markers of UPR activation (p-PERK and p-eIF2α) concomitantly with neuronal markers (NeuN and PGP9.5) and pathology markers (beta-amyloid and tau) in the olfactory bulb, piriform cortex, entorhinal cortex and the CA1 region of the hippocampus in AD and normal cases. We show that UPR activation, as indicated by p-PERK and p-eIF2α expression, is significantly increased throughout the olfactory system in AD cases with low (Braak stage III-IV) and high-level (Braak stage V-VI) pathology. We further show that UPR activation occurs in the mitral cells and in the anterior olfactory nucleus of the olfactory bulb where tau and amyloid pathology is abundant. However, UPR activation is not present in neurons when they contain NFTs and only rarely occurs in neurons containing diffuse tau aggregates. We conclude that UPR activation is prevalent in all regions of the olfactory system and support previous findings suggesting that UPR activation likely precedes NFT formation. Our data indicate that chronic UPR activation in the olfactory system might contribute to the olfactory dysfunction that occurs early in the pathogenesis of AD.
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