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Yang C, Liu G, Chen X, Le W. Cerebellum in Alzheimer's disease and other neurodegenerative diseases: an emerging research frontier. MedComm (Beijing) 2024; 5:e638. [PMID: 39006764 PMCID: PMC11245631 DOI: 10.1002/mco2.638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 06/04/2024] [Accepted: 06/12/2024] [Indexed: 07/16/2024] Open
Abstract
The cerebellum is crucial for both motor and nonmotor functions. Alzheimer's disease (AD), alongside other dementias such as vascular dementia (VaD), Lewy body dementia (DLB), and frontotemporal dementia (FTD), as well as other neurodegenerative diseases (NDs) like Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), Huntington's disease (HD), and spinocerebellar ataxias (SCA), are characterized by specific and non-specific neurodegenerations in central nervous system. Previously, the cerebellum's significance in these conditions was underestimated. However, advancing research has elevated its profile as a critical node in disease pathology. We comprehensively review the existing evidence to elucidate the relationship between cerebellum and the aforementioned diseases. Our findings reveal a growing body of research unequivocally establishing a link between the cerebellum and AD, other forms of dementia, and other NDs, supported by clinical evidence, pathological and biochemical profiles, structural and functional neuroimaging data, and electrophysiological findings. By contrasting cerebellar observations with those from the cerebral cortex and hippocampus, we highlight the cerebellum's distinct role in the disease processes. Furthermore, we also explore the emerging therapeutic potential of targeting cerebellum for the treatment of these diseases. This review underscores the importance of the cerebellum in these diseases, offering new insights into the disease mechanisms and novel therapeutic strategies.
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Affiliation(s)
- Cui Yang
- Institute of Neurology Sichuan Provincial People's Hospital School of Medicine University of Electronic Science and Technology of China Chengdu China
| | - Guangdong Liu
- Institute of Neurology Sichuan Provincial People's Hospital School of Medicine University of Electronic Science and Technology of China Chengdu China
| | - Xi Chen
- Institute of Neurology Sichuan Provincial People's Hospital School of Medicine University of Electronic Science and Technology of China Chengdu China
| | - Weidong Le
- Institute of Neurology Sichuan Provincial People's Hospital School of Medicine University of Electronic Science and Technology of China Chengdu China
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Wang Y, Hartmann K, Thies E, Mohammadi B, Altmeppen H, Sepulveda-Falla D, Glatzel M, Krasemann S. Loss of Homeostatic Microglia Signature in Prion Diseases. Cells 2022; 11:cells11192948. [PMID: 36230910 PMCID: PMC9563810 DOI: 10.3390/cells11192948] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 09/12/2022] [Accepted: 09/15/2022] [Indexed: 11/16/2022] Open
Abstract
Prion diseases are neurodegenerative diseases that affect humans and animals. They are always fatal and, to date, no treatment exists. The hallmark of prion disease pathophysiology is the misfolding of an endogenous protein, the cellular prion protein (PrPC), into its disease-associated isoform PrPSc. Besides the aggregation and deposition of misfolded PrPSc, prion diseases are characterized by spongiform lesions and the activation of astrocytes and microglia. Microglia are the innate immune cells of the brain. Activated microglia and astrocytes represent a common pathological feature in neurodegenerative disorders. The role of activated microglia has already been studied in prion disease mouse models; however, it is still not fully clear how they contribute to disease progression. Moreover, the role of microglia in human prion diseases has not been thoroughly investigated thus far, and specific molecular pathways are still undetermined. Here, we review the current knowledge on the different roles of microglia in prion pathophysiology. We discuss microglia markers that are also dysregulated in other neurodegenerative diseases including microglia homeostasis markers. Data on murine and human brain tissues show that microglia are highly dysregulated in prion diseases. We highlight here that the loss of homeostatic markers may especially stand out.
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Tahir W, Thapa S, Schatzl HM. Astrocyte in prion disease: a double-edged sword. Neural Regen Res 2022; 17:1659-1665. [PMID: 35017412 PMCID: PMC8820723 DOI: 10.4103/1673-5374.332202] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 04/08/2021] [Accepted: 07/22/2021] [Indexed: 11/04/2022] Open
Abstract
Prion diseases are infectious protein misfolding disorders of the central nervous system that result from misfolding of the cellular prion protein (PrPC) into the pathologic isoform PrPSc. Pathologic hallmarks of prion disease are depositions of pathological prion protein PrPSc, neuronal loss, spongiform degeneration and astrogliosis in the brain. Prion diseases affect human and animals, there is no effective therapy, and they invariably remain fatal. For a long time, neuronal loss was considered the sole reason for neurodegeneration in prion pathogenesis, and the contribution of non-neuronal cells like microglia and astrocytes was considered less important. Recent evidence suggests that neurodegeneration during prion pathogenesis is a consequence of a complex interplay between neuronal and non-neuronal cells in the brain, but the exact role of these non-neuronal cells during prion pathology is still elusive. Astrocytes are non-neuronal cells that regulate brain homeostasis under physiological conditions. However, astrocytes can deposit PrPSc aggregates and propagate prions in prion-infected brains. Additionally, sub-populations of reactive astrocytes that include neurotrophic and neurotoxic species have been identified, differentially expressed in the brain during prion infection. Revealing the exact role of astrocytes in prion disease is hampered by the lack of in vitro models of prion-infected astrocytes. Recently, we established a murine astrocyte cell line persistently infected with mouse-adapted prions, and showed how such astrocytes differentially process various prion strains. Considering the complexity of the role of astrocytes in prion pathogenesis, we need more in vitro and in vivo models for exploring the contribution of sub-populations of reactive astrocytes, their differential regulation of signaling cascades, and the interaction with neurons and microglia during prion pathogenesis. This will help to establish novel in vivo models and define new therapeutic targets against prion diseases. In this review, we will discuss the complex role of astrocytes in prion disease, the existing experimental resources, the challenges to analyze the contribution of astrocytes in prion disease pathogenesis, and future strategies to improve the understanding of their role in prion disease.
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Affiliation(s)
- Waqas Tahir
- Department of Comparative Biology & Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
- Calgary Prion Research Unit, University of Calgary, Calgary, AB, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
| | - Simrika Thapa
- Department of Comparative Biology & Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
- Calgary Prion Research Unit, University of Calgary, Calgary, AB, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
| | - Hermann M. Schatzl
- Department of Comparative Biology & Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
- Calgary Prion Research Unit, University of Calgary, Calgary, AB, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
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Pankiewicz JE, Lizińczyk AM, Franco LA, Diaz JR, Martá-Ariza M, Sadowski MJ. Absence of Apolipoprotein E is associated with exacerbation of prion pathology and promotes microglial neurodegenerative phenotype. Acta Neuropathol Commun 2021; 9:157. [PMID: 34565486 PMCID: PMC8474943 DOI: 10.1186/s40478-021-01261-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Accepted: 09/08/2021] [Indexed: 12/27/2022] Open
Abstract
Prion diseases or prionoses are a group of rapidly progressing and invariably fatal neurodegenerative diseases. The pathogenesis of prionoses is associated with self-replication and connectomal spread of PrPSc, a disease specific conformer of the prion protein. Microglia undergo activation early in the course of prion pathogenesis and exert opposing roles in PrPSc mediated neurodegeneration. While clearance of PrPSc and apoptotic neurons have disease-limiting effect, microglia-driven neuroinflammation bears deleterious consequences to neuronal networks. Apolipoprotein (apo) E is a lipid transporting protein with pleiotropic functions, which include controlling of the phagocytic and inflammatory characteristics of activated microglia in neurodegenerative diseases. Despite the significance of microglia in prion pathogenesis, the role of apoE in prionoses has not been established. We showed here that infection of wild type mice with 22L mouse adapted scrapie strain is associated with significant increase in the total brain apoE protein and mRNA levels and also with a conspicuous cell-type shift in the apoE expression. There is reduced expression of apoE in activated astrocytes and marked upregulation of apoE expression by activated microglia. We also showed apoE ablation exaggerates PrPSc mediated neurodegeneration. Apoe−/− mice have shorter disease incubation period, increased load of spongiform lesion, pronounced neuronal loss, and exaggerated astro and microgliosis. Astrocytes of Apoe−/− mice display salient upregulation of transcriptomic markers defining A1 neurotoxic astrocytes while microglia show upregulation of transcriptomic markers characteristic for microglial neurodegenerative phenotype. There is impaired clearance of PrPSc and dying neurons by microglia in Apoe−/− mice along with increased level of proinflammatory cytokines. Our work indicates that apoE absence renders clearance of PrPSc and dying neurons by microglia inefficient, while the excess of neuronal debris promotes microglial neurodegenerative phenotype aggravating the vicious cycle of neuronal death and neuroinflammation.
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