Potential Modes of Intercellular Alpha-Synuclein Transmission

Intracellular aggregates of the alpha-synuclein protein result in cell loss and dysfunction in Parkinson’s disease and atypical parkinsonism, such as multiple system atrophy and dementia with Lewy bodies. Each of these neurodegenerative conditions, known collectively as alpha-synucleinopathies, may be characterized by a different suite of molecular triggers that initiate pathogenesis. The mechanisms whereby alpha-synuclein aggregates in turn mediate cytotoxicity also remain to be fully elucidated. However, recent studies have implicated the cell-to-cell spread of alpha-synuclein as the major mode of disease propagation between brain regions during disease progression. Here, we review the current evidence for different modes of alpha-synuclein cellular release, movement and uptake, including exocytosis, exosomes, tunnelling nanotubes, glymphatic flow and endocytosis. A more detailed understanding of the major modes by which alpha-synuclein pathology spreads throughout the brain may provide new targets for therapies that halt the progression of disease.

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Extracellular Interactions of Alpha-Synuclein in Multiple System Atrophy

International Journal of Molecular Sciences ◽

10.3390/ijms19124129 ◽

2018 ◽

Vol 19 (12) ◽

pp. 4129 ◽

Cited By ~ 6

Author(s):

Dario Valdinocci ◽

Rowan Radford ◽

Michael Goulding ◽

Junna Hayashi ◽

Roger Chung ◽

...

Keyword(s):

Multiple System Atrophy ◽

Disease Process ◽

Neuronal Cell ◽

Cell Loss ◽

Cell Types ◽

Brain Regions ◽

Alpha Synuclein ◽

Current Evidence ◽

Extracellular Milieu ◽

The Brain

Multiple system atrophy, characterized by atypical Parkinsonism, results from central nervous system (CNS) cell loss and dysfunction linked to aggregates of the normally pre-synaptic α-synuclein protein. Mostly cytoplasmic pathological α-synuclein inclusion bodies occur predominantly in oligodendrocytes in affected brain regions and there is evidence that α-synuclein released by neurons is taken up preferentially by oligodendrocytes. However, extracellular α-synuclein has also been shown to interact with other neural cell types, including astrocytes and microglia, as well as extracellular factors, mediating neuroinflammation, cell-to-cell spread and other aspects of pathogenesis. Here, we review the current evidence for how α-synuclein present in the extracellular milieu may act at the cell surface to drive components of disease progression. A more detailed understanding of the important extracellular interactions of α-synuclein with neuronal and non-neuronal cell types both in the brain and periphery may provide new therapeutic targets to modulate the disease process.

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14-3-3 mitigates alpha-synuclein aggregation and toxicity in the in vivo preformed fibril model

10.1101/2020.11.17.387415 ◽

2020 ◽

Author(s):

Rachel Underwood ◽

Mary Gannon ◽

Aneesh Pathak ◽

Navya Kapa ◽

Sidhanth Chandra ◽

...

Keyword(s):

Social Dominance ◽

Lewy Bodies ◽

Neuronal Loss ◽

Cell Loss ◽

Brain Regions ◽

Alpha Synuclein ◽

Dopaminergic Cell ◽

The Impact

AbstractAlpha-synuclein (αsyn) is the key component of proteinaceous aggregates termed Lewy Bodies (LBs) that pathologically define a group of disorders known as synucleinopathies, including Parkinson’s Disease (PD) and Dementia with Lewy Bodies (DLB). αSyn is hypothesized to misfold and spread throughout the brain in a prion-like fashion. Transmission of αsyn necessitates the release of misfolded αsyn from one cell and the uptake of that αsyn by another, in which it can template the misfolding of endogenous αsyn upon cell internalization. 14-3-3 proteins are a family of highly expressed brain proteins that are neuroprotective in multiple PD models. We have previously shown that 14-3-3θ acts as a chaperone to reduce αsyn aggregation, cell-to-cell transmission, and neurotoxicity in the in vitro pre-formed fibril (PFF) model. In this study, we expanded our studies to test the impact of 14-3-3s on αsyn toxicity in the in vivo αsyn PFF model. We used both transgenic expression models and adenovirus associated virus (AAV)-mediated expression to examine whether 14-3-3 manipulation impacts behavioral deficits, αsyn aggregation, and neuronal loss in the PFF model. 14-3-3θ transgene overexpression in cortical and amygdala regions rescued social dominance deficits induced by PFFs at 6 months post injection, whereas 14-3-3 inhibition by transgene expression of the competitive 14-3-3 peptide inhibitor difopein in the cortex and amygdala accelerated social dominance deficits. The behavioral rescue by 14-3-3θ overexpression was associated with delayed αsyn aggregation induced by PFFs in these brain regions. Conversely, 14-3-3 inhibition by difopein in the cortex and amygdala accelerated αsyn aggregation and cortical pyramidal neuron loss induced by PFFs. 14-3-3θ overexpression by AAV in the substantia nigra (SN) also delayed αsyn aggregation in the SN and partially rescued PFF-induced dopaminergic cell loss in the SN. 14-3-3 inhibition in the SN accelerated nigral αsyn aggregation and increased PFF-induced dopaminergic cell loss. These data indicate a neuroprotective role for 14-3-3θ against αsyn toxicity in vivo.

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Multiple system atrophy-associated oligodendroglial protein p25α stimulates formation of novel α-synuclein strain with enhanced neurodegenerative potential

Acta Neuropathologica ◽

10.1007/s00401-021-02316-0 ◽

2021 ◽

Author(s):

Nelson Ferreira ◽

Hjalte Gram ◽

Zachary A. Sorrentino ◽

Emil Gregersen ◽

Sissel Ida Schmidt ◽

...

Keyword(s):

Multiple System Atrophy ◽

Protein Misfolding ◽

Resonance Energy Transfer ◽

Lewy Bodies ◽

Resonance Energy ◽

Alpha Synuclein ◽

Striatal Neurons ◽

End Stage ◽

Intracellular Aggregates

AbstractPathology consisting of intracellular aggregates of alpha-Synuclein (α-Syn) spread through the nervous system in a variety of neurodegenerative disorders including Parkinson’s disease, dementia with Lewy bodies, and multiple system atrophy. The discovery of structurally distinct α-Syn polymorphs, so-called strains, supports a hypothesis where strain-specific structures are templated into aggregates formed by native α-Syn. These distinct strains are hypothesised to dictate the spreading of pathology in the tissue and the cellular impact of the aggregates, thereby contributing to the variety of clinical phenotypes. Here, we present evidence of a novel α-Syn strain induced by the multiple system atrophy-associated oligodendroglial protein p25α. Using an array of biophysical, biochemical, cellular, and in vivo analyses, we demonstrate that compared to α-Syn alone, a substoichiometric concentration of p25α redirects α-Syn aggregation into a unique α-Syn/p25α strain with a different structure and enhanced in vivo prodegenerative properties. The α-Syn/p25α strain induced larger inclusions in human dopaminergic neurons. In vivo, intramuscular injection of preformed fibrils (PFF) of the α-Syn/p25α strain compared to α-Syn PFF resulted in a shortened life span and a distinct anatomical distribution of inclusion pathology in the brain of a human A53T transgenic (line M83) mouse. Investigation of α-Syn aggregates in brain stem extracts of end-stage mice demonstrated that the more aggressive phenotype of the α-Syn/p25α strain was associated with an increased load of α-Syn aggregates based on a Förster resonance energy transfer immunoassay and a reduced α-Syn aggregate seeding activity based on a protein misfolding cyclic amplification assay. When injected unilaterally into the striata of wild-type mice, the α-Syn/p25α strain resulted in a more-pronounced motoric phenotype than α-Syn PFF and exhibited a “tropism” for nigro-striatal neurons compared to α-Syn PFF. Overall, our data support a hypothesis whereby oligodendroglial p25α is responsible for generating a highly prodegenerative α-Syn strain in multiple system atrophy.

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Parkinsonism, Parkinson’s disease, and related conditions

Oxford Textbook of Geriatric Medicine ◽

10.1093/med/9780198701590.003.0116 ◽

2017 ◽

pp. 897-906

Author(s):

John V. Hindle ◽

Sion Jones ◽

Glesni Davies

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Older People ◽

Lewy Bodies ◽

Cell Loss ◽

Brain Regions ◽

Motor Symptoms ◽

Advanced Care Planning ◽

Non Motor Symptoms

Parkinson’s disease (PD) is a progressive neurodegenerative condition characterized clinically by fatiguable bradykinesia, rigidity and tremor and pathologically by deposition of Lewy bodies and cell loss in the substantia nigra and other brain regions. Parkinsonism is the term used to describe the clinical features of conditions resembling PD. Their management requires specialist assessment and a multidisciplinary approach. Levodopa remains the mainstay of treatment for PD. Although other treatments are used, older people are more sensitive to their side effects. Non-motor symptoms, particularly neuropsychiatric problems, significantly impact quality of life and need special consideration in older people. Towards the later stage of the disease, management can be complex, and should involve advanced care planning.

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Novel antibodies detect additional α-synuclein pathology in synucleinopathies: potential development for immunotherapy

Alzheimer s Research & Therapy ◽

10.1186/s13195-020-00727-x ◽

2020 ◽

Vol 12 (1) ◽

Author(s):

Jacqui T. Nimmo ◽

Ajay Verma ◽

Jean-Cosme Dodart ◽

Chang Yi Wang ◽

Jimmy Savistchenko ◽

...

Keyword(s):

Human Brain ◽

Guinea Pigs ◽

Lewy Bodies ◽

Insular Cortex ◽

Internal Capsule ◽

Brain Regions ◽

Alpha Synuclein ◽

Human Brain Tissue ◽

Lewy Neurites ◽

Slot Blot Analysis

Abstract Background Alpha-synuclein (α-Syn) aggregation is the primary characteristic of synucleinopathies including Parkinson’s disease (PD), dementia with Lewy bodies (DLB) and multiple system atrophy (MSA). Immunotherapy targeting α-Syn has shown promising results in animal models of the disease. This study investigates the target specificity of three different active vaccines for pathological α-Syn aggregates found in human brain tissue from synucleinopathies. Methods Guinea pigs were immunised with 3 vaccines developed by United Neuroscience, and IgG fractions purified from the resulting immune sera (IGG-1, IGG-2 or IGG-3) were used to perform immunohistochemical staining of human cases of PD, DLB and MSA. The resulting immunoreactivity was compared to a commercially available α-Syn antibody from Novacastra (NOV) commonly used for diagnostic purposes. Images were captured from the substantia nigra (SN), temporal lobe, internal capsule, insular cortex and putamen and quantified for the percentage area with α-Syn immunoreactivity. Lewy bodies (LB) and Lewy neurites (LN) were further analysed in PD and DLB cases. Results Vaccine-generated antibodies detected more α-Syn pathology compared to NOV. The levels of α-Syn immunoreactivity varied between brain region and disease type with IGG-3 recognising the highest levels of α-Syn in most cases and in all brain regions that are affected early in disease progression. IGG-3 had a high recognition for glial inclusions found in MSA which are known to have a more compact conformation. Slot blot analysis confirmed the specificity of IGG-3 for native oligomers and fibrillar α-Syn. Higher levels of α-Syn were recognised by IGG-2 in cortical regions, and by IGG-3 in SN of PD and DLB cases. This was due to increased immunolabelling of LNs in these brain regions suggesting that IGG-2 and IGG-3 recognised additional α-Syn pathology compared to IGG-1 and NOV. Whether the unique binding properties of the antibodies produced in guinea pigs will translate in the clinic remains to be addressed, which is the main limitation of this study. Conclusions These vaccines induce antibodies that bind α-Syn oligomers and aggregates in the human brain and specifically support the choice of the vaccine generating IGG-3 (i.e. UB-312) as a candidate for clinical trials for synucleinopathies.

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Behavioral Deficits and Brain α-Synuclein and Phosphorylated Serine-129 α-Synuclein in Male and Female Mice Overexpressing Human α-Synuclein

Journal of Alzheimer s Disease ◽

10.3233/jad-200983 ◽

2020 ◽

pp. 1-19

Author(s):

Lilit Gabrielyan ◽

Honghui Liang ◽

Artem Minalyan ◽

Asa Hatami ◽

Varghese John ◽

...

Keyword(s):

Lewy Bodies ◽

Distribution Patterns ◽

Brain Regions ◽

Alpha Synuclein ◽

Nigrostriatal System ◽

Brain Areas ◽

Male And Female ◽

Female Mice ◽

Motor Behaviors ◽

Lateral Parabrachial Nucleus

Background: Alpha-synuclein (α-syn) is a molecule involved in pathology of Parkinson’s disease, and 90%of α-syn in Lewy bodies is phosphorylated at serine 129 (pS129 α-syn). Objective: To assess motor and non-motor behaviors in male and female mice overexpressing human α-syn under Thy1 promoter (Thy1-α-syn) and wild type (wt) littermates. Methods: Motor and non-motor behaviors brain human α-syn levels by ELISA, and mapped α-syn and pS129 α-syn in the brain by immunohistochemistry. Results: Male and female wt littermates did not show differences in the behavioral tests. Male Thy1-α-syn mice displayed more severe impairments than female counterparts in cotton nesting, pole tests, adhesive removal, finding buried food, and marble burying. Concentrations of human α-syn in the olfactory regions, cortex, nigrostriatal system, and dorsal medulla were significantly increased in Thy1-α-syn mice, higher in males than females. Immunoreactivity of α-syn was not simply increased in Thy1-α-syn mice but had altered localization in somas and fibers in a few brain areas. Abundant pS129 α-syn existed in many brain areas of Thy1-α-syn mice, while there was none or only a small amount in a few brain regions of wt mice. The substantia nigra, olfactory regions, amygdala, lateral parabrachial nucleus, and dorsal vagal complex displayed different distribution patterns between wt and transgenic mice, but not between sexes. Conclusion: The severer abnormal behaviors in male than female Thy1-α-syn mice may be related to higher brain levels of human α-syn, in the absence of sex differences in the altered brain immunoreactivity patterns of α-syn and pS129 α-syn.

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Effects of Alpha-Synuclein Targeted Antisense Oligonucleotides on Lewy Body-Like Pathology and Behavioral Disturbances Induced by Injections of Pre-Formed Fibrils in the Mouse Motor Cortex

Journal of Parkinson s Disease ◽

10.3233/jpd-212566 ◽

2021 ◽

pp. 1-24

Author(s):

Sydney Weber Boutros ◽

Jacob Raber ◽

Vivek K. Unni

Keyword(s):

Motor Cortex ◽

Cognitive Performance ◽

Antisense Oligonucleotides ◽

Therapeutic Potential ◽

Lewy Bodies ◽

Brain Regions ◽

Alpha Synuclein ◽

Primary Component ◽

Long Term Effects ◽

Behavioral Disturbances

Background: Alpha-synuclein (αsyn) characterizes neurodegenerative diseases known as synucleinopathies. The phosphorylated form (psyn) is the primary component of protein aggregates known as Lewy bodies (LBs), which are the hallmark of diseases such as Parkinson’s disease (PD). Synucleinopathies might spread in a prion-like fashion, leading to a progressive emergence of symptoms over time. αsyn pre-formed fibrils (PFFs) induce LB-like pathology in wild-type (WT) mice, but questions remain about their progressive spread and their associated effects on behavioral performance. Objective: To characterize the behavioral, cognitive, and pathological long-term effects of LB-like pathology induced after bilateral motor cortex PFF injection in WT mice and to assess the ability of mouse αsyn-targeted antisense oligonucleotides (ASOs) to ameliorate those effects. Methods: We induced LB-like pathology in the motor cortex and connected brain regions of male WT mice using PFFs. Three months post-PFF injection (mpi), we assessed behavioral and cognitive performance. We then delivered a targeted ASO via the ventricle and assessed behavioral and cognitive performance 5 weeks later, followed by pathological analysis. Results: At 3 and 6 mpi, PFF-injected mice showed mild, progressive behavioral deficits. The ASO reduced total αsyn and psyn protein levels, and LB-like pathology, but was also associated with some deleterious off-target effects not involving lowering of αsyn, such as a decline in body weight and impairments in motor function. Conclusions: These results increase understanding of the progressive nature of the PFF model and support the therapeutic potential of ASOs, though more investigation into effects of ASO-mediated reduction in αsyn on brain function is needed.

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Intrastriatal injection of preformed alpha-synuclein fibrils alters central and peripheral immune cell profiles in non-transgenic mice

Journal of Neuroinflammation ◽

10.1186/s12974-019-1636-8 ◽

2019 ◽

Vol 16 (1) ◽

Cited By ~ 9

Author(s):

Rachael H. Earls ◽

Kelly B. Menees ◽

Jaegwon Chung ◽

James Barber ◽

Claire-Anne Gutekunst ◽

...

Keyword(s):

Immune Responses ◽

Immune Cell ◽

Lewy Bodies ◽

Brain Regions ◽

Alpha Synuclein ◽

Molecular Pattern ◽

Immune Phenotypes ◽

Spleen And Lymph Nodes ◽

The Brain ◽

Intrastriatal Injection

AbstractParkinson’s disease (PD) is characterized by the accumulation of alpha-synuclein (α-syn) inclusions, the major component of Lewy bodies. Extracellular α-syn aggregates act as a damage-associated molecular pattern (DAMP) and the presence of autoantibodies against α-syn species in the cerebrospinal fluid and the serum of PD patients implicate the involvement of innate and adaptive immune responses. In non-transgenic (Tg) mice, intrastriatal injection of preformed fibril (PFF) α-syn results in widespread pathologic α-syn inclusions in the CNS. While the PFF model has been broadly utilized to study the mechanistic relationship between α-syn transmission and other neuropathological phenotypes, the immune phenotypes in this model are not clearly demonstrated. This study aimed to characterize the immune phenotypes during pathologic α-syn propagation by utilizing PFF α-syn–injected non-tg mice. Here, we showed that pathologic α-syn inclusions are prevalent in various brain regions and the gut at 5 months post injection (p.i.), preceding the degeneration of dopaminergic neurons in substantia nigra (SN). We discovered a distinct inflammatory response involving both activation of microglia and astrocytes and infiltration of B, CD4+ T, CD8+ T, and natural killer cells in the brain at 5 months p.i. Moreover, PFF α-syn–injected mice display significant alterations in the frequency and number of leukocyte subsets in the spleen and lymph nodes with minimum alterations in the blood. Our data provide primary evidence that intracerebral-initiated synucleinopathies in non-tg mice alter immune cell profiles both in the CNS and peripheral lymphoid organs. Furthermore, our data provides support for utilizing this mouse model to assess the mechanistic connection between immune responses and synuclein pathology.

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Behavioural and dopaminergic changes in double mutated human A30P*A53T alpha-synuclein transgenic mouse model of Parkinson´s disease

Scientific Reports ◽

10.1038/s41598-019-54034-z ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 2

Author(s):

Tommi Kilpeläinen ◽

Ulrika H. Julku ◽

Reinis Svarcbahs ◽

Timo T. Myöhänen

Keyword(s):

Locomotor Activity ◽

Transgenic Mouse ◽

Mouse Strain ◽

Early Onset ◽

Point Mutations ◽

Lewy Bodies ◽

Cell Loss ◽

Alpha Synuclein ◽

Transgenic Mouse Strain ◽

Main Component

AbstractAlpha-synuclein (aSyn) is the main component of Lewy bodies, the histopathological marker in Parkinson’s disease (PD), and point mutations and multiplications of the aSyn coding SNCA gene correlate with early onset PD. Therefore, various transgenic mouse models overexpressing native or point-mutated aSyn have been developed. Although these models show highly increased aSyn expression they rarely capture dopaminergic cell loss and show a behavioural phenotype only at old age, whereas SNCA mutations are risk factors for PD with earlier onset. The aim of our study was to re-characterize a transgenic mouse strain carrying both A30P and A53T mutated human aSyn. Our study revealed decreased locomotor activity for homozygous transgenic mice starting from 3 months of age which was different from previous studies with this mouse strain that had behavioural deficits starting only after 7–9 months. Additionally, we found a decreased amphetamine response in locomotor activity and decreased extracellular dopaminergic markers in the striatum and substantia nigra with significantly elevated levels of aSyn oligomers. In conclusion, homozygous transgenic A30P*A53T aSyn mice capture several phenotypes of PD with early onset and could be a useful tool for aSyn studies.

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C-Abl Inhibition; A Novel Therapeutic Target for Parkinson's Disease

CNS & Neurological Disorders - Drug Targets ◽

10.2174/1871527316666170602101538 ◽

2018 ◽

Vol 17 (1) ◽

pp. 14-21 ◽

Cited By ~ 13

Author(s):

Abdelrahman Ibrahim Abushouk ◽

Ahmed Negida ◽

Rasha Abdelsalam Elshenawy ◽

Hossam Zein ◽

Ali M. Hammad ◽

...

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Drug Targets ◽

Experimental Studies ◽

Lewy Bodies ◽

Alpha Synuclein ◽

Current Evidence ◽

Future Research ◽

Neuroprotective Effects ◽

Human Trial

Parkinson's disease (PD) is the most prevalent movement disorder in the world. The major pathological hallmarks of PD are death of dopaminergic neurons and the formation of Lewy bodies. At the moment, there is no cure for PD; current treatments are symptomatic. Investigators are searching for neuroprotective agents and disease modifying strategies to slow the progress of neurodegeneration. However, due to lack of data about the main pathological sequence of PD, many drug targets failed to provide neuroprotective effects in human trials. Recent evidence suggests the involvement of C-Abelson (c-Abl) tyrosine kinase enzyme in the pathogenesis of PD. Through parkin inactivation, alpha synuclein aggregation, and impaired autophagy of toxic elements. Experimental studies showed that (1) c-Abl activation is involved in neurodegeneration and (2) c-Abl inhibition shows neuroprotective effects and prevents dopaminergic neuronal' death. Current evidence from experimental studies and the first in-human trial shows that c-Abl inhibition holds the promise for neuroprotection against PD and therefore, justifies the movement towards larger clinical trials. In this review article, we discussed the role of c-Abl in PD pathogenesis and the findings of preclinical experiments and the first in-human trial. In addition, based on lessons from the last decade and current preclinical evidence, we provide recommendations for future research in this area.

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