Microglial exosomes facilitate α-synuclein transmission in Parkinson’s disease

Abstract Accumulation of neuronal α-synuclein is a prominent feature in Parkinson’s disease. More recently, such abnormal protein aggregation has been reported to spread from cell to cell and exosomes are considered as important mediators. The focus of such research, however, has been primarily in neurons. Given the increasing recognition of the importance of non-cell autonomous-mediated neurotoxicity, it is critical to investigate the contribution of glia to α-synuclein aggregation and spread. Microglia are the primary phagocytes in the brain and have been well-documented as inducers of neuroinflammation. How and to what extent microglia and their exosomes impact α-synuclein pathology has not been well delineated. We report here that when treated with human α-synuclein preformed fibrils, exosomes containing α-synuclein released by microglia are fully capable of inducing protein aggregation in the recipient neurons. Additionally, when combined with microglial proinflammatory cytokines, these exosomes further increased protein aggregation in neurons. Inhibition of exosome synthesis in microglia reduced α-synuclein transmission. The in vivo significance of these exosomes was demonstrated by stereotaxic injection of exosomes isolated from α-synuclein preformed fibrils treated microglia into the mouse striatum. Phosphorylated α-synuclein was observed in multiple brain regions consistent with their neuronal connectivity. These animals also exhibited neurodegeneration in the nigrostriatal pathway in a time-dependent manner. Depleting microglia in vivo dramatically suppressed the transmission of α-synuclein after stereotaxic injection of preformed fibrils. Mechanistically, we report here that α-synuclein preformed fibrils impaired autophagy flux by upregulating PELI1, which in turn, resulted in degradation of LAMP2 in activated microglia. More importantly, by purifying microglia/macrophage derived exosomes in the CSF of Parkinson’s disease patients, we confirmed the presence of α-synuclein oligomer in CD11b+ exosomes, which were able to induce α-synuclein aggregation in neurons, further supporting the translational aspect of this study. Taken together, our study supports the view that microglial exosomes contribute to the progression of α-synuclein pathology and therefore, they may serve as a promising therapeutic target for Parkinson’s disease.

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Neuroinflammation and protein pathology in Parkinson’s disease dementia

Acta Neuropathologica Communications ◽

10.1186/s40478-020-01083-5 ◽

2020 ◽

Vol 8 (1) ◽

Cited By ~ 1

Author(s):

Antonina Kouli ◽

Marta Camacho ◽

Kieren Allinson ◽

Caroline H. Williams-Gray

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

T Lymphocytes ◽

Substantia Nigra ◽

Amyloid Β ◽

Brain Regions ◽

Parkinson’S Disease Dementia ◽

Activated Microglia ◽

Cell Counts ◽

The Brain

AbstractParkinson’s disease dementia is neuropathologically characterized by aggregates of α-synuclein (Lewy bodies) in limbic and neocortical areas of the brain with additional involvement of Alzheimer’s disease-type pathology. Whilst immune activation is well-described in Parkinson’s disease (PD), how it links to protein aggregation and its role in PD dementia has not been explored. We hypothesized that neuroinflammatory processes are a critical contributor to the pathology of PDD. To address this hypothesis, we examined 7 brain regions at postmortem from 17 PD patients with no dementia (PDND), 11 patients with PD dementia (PDD), and 14 age and sex-matched neurologically healthy controls. Digital quantification after immunohistochemical staining showed a significant increase in the severity of α-synuclein pathology in the hippocampus, entorhinal and occipitotemporal cortex of PDD compared to PDND cases. In contrast, there was no difference in either tau or amyloid-β pathology between the groups in any of the examined regions. Importantly, we found an increase in activated microglia in the amygdala of demented PD brains compared to controls which correlated significantly with the extent of α-synuclein pathology in this region. Significant infiltration of CD4+ T lymphocytes into the brain parenchyma was commonly observed in PDND and PDD cases compared to controls, in both the substantia nigra and the amygdala. Amongst PDND/PDD cases, CD4+ T cell counts in the amygdala correlated with activated microglia, α-synuclein and tau pathology. Upregulation of the pro-inflammatory cytokine interleukin 1β was also evident in the substantia nigra as well as the frontal cortex in PDND/PDD versus controls with a concomitant upregulation in Toll-like receptor 4 (TLR4) in these regions, as well as the amygdala. The evidence presented in this study show an increased immune response in limbic and cortical brain regions, including increased microglial activation, infiltration of T lymphocytes, upregulation of pro-inflammatory cytokines and TLR gene expression, which has not been previously reported in the postmortem PDD brain.

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Growth Factor Therapy for Parkinson’s Disease: Alternative Delivery Systems

Journal of Parkinson s Disease ◽

10.3233/jpd-212662 ◽

2021 ◽

pp. 1-7

Author(s):

Sarah Jarrin ◽

Abrar Hakami ◽

Ben Newland ◽

Eilís Dowd

Keyword(s):

Parkinson’S Disease ◽

Gene Therapy ◽

Parkinson's Disease ◽

Growth Factors ◽

Growth Factor ◽

Ex Vivo ◽

Brain Regions ◽

Delivery Systems ◽

Alternative Delivery

Despite decades of research and billions in global investment, there remains no preventative or curative treatment for any neurodegenerative condition, including Parkinson’s disease (PD). Arguably, the most promising approach for neuroprotection and neurorestoration in PD is using growth factors which can promote the growth and survival of degenerating neurons. However, although neurotrophin therapy may seem like the ideal approach for neurodegenerative disease, the use of growth factors as drugs presents major challenges because of their protein structure which creates serious hurdles related to accessing the brain and specific targeting of affected brain regions. To address these challenges, several different delivery systems have been developed, and two major approaches—direct infusion of the growth factor protein into the target brain region and in vivo gene therapy—have progressed to clinical trials in patients with PD. In addition to these clinically evaluated approaches, a range of other delivery methods are in various degrees of development, each with their own unique potential. This review will give a short overview of some of these alternative delivery systems, with a focus on ex vivo gene therapy and biomaterial-aided protein and gene delivery, and will provide some perspectives on their potential for clinical development and translation.

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The Efficacy of Iron Chelators for Removing Iron from Specific Brain Regions and the Pituitary—Ironing out the Brain

Pharmaceuticals ◽

10.3390/ph12030138 ◽

2019 ◽

Vol 12 (3) ◽

pp. 138 ◽

Cited By ~ 5

Author(s):

Robert R. Crichton ◽

Roberta J. Ward ◽

Robert C. Hider

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Iron Chelation ◽

Brain Regions ◽

Beta Thalassemia ◽

Excess Iron ◽

New Class ◽

Clinical Conditions ◽

The Brain

Iron chelation therapy, either subcutaneous or orally administered, has been used successfully in various clinical conditions. The removal of excess iron from various tissues, e.g., the liver spleen, heart, and the pituitary, in beta thalassemia patients, has become an essential therapy to prolong life. More recently, the use of deferiprone to chelate iron from various brain regions in Parkinson’s Disease and Friederich’s Ataxia has yielded encouraging results, although the side effects, in <2% of Parkinson’s Disease(PD) patients, have limited its long-term use. A new class of hydroxpyridinones has recently been synthesised, which showed no adverse effects in preliminary trials. A vital question remaining is whether inflammation may influence chelation efficacy, with a recent study suggesting that high levels of inflammation may diminish the ability of the chelator to bind the excess iron.

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Glucocerebrosidase reduces the spread of protein aggregation in a Drosophila melanogaster model of neurodegeneration by regulating proteins trafficked by extracellular vesicles

10.1101/2020.05.15.097766 ◽

2020 ◽

Author(s):

Kathryn A. Jewett ◽

Ruth E. Thomas ◽

Chi Q. Phan ◽

Gillian Milstein ◽

Selina Yu ◽

...

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Risk Factor ◽

Protein Aggregation ◽

Disease Progression ◽

Extracellular Vesicles ◽

Genetic Risk ◽

Protein Aggregates ◽

Genetic Risk Factor ◽

The Brain

AbstractAbnormal protein aggregation within neurons is a key pathologic feature of Parkinson’s disease (PD). The spread of protein aggregates in the brain is associated with clinical disease progression, but how this occurs remains unclear. Mutations in the gene glucosidase, beta acid 1 (GBA), which encodes the lysosomal enzyme glucocerebrosidase (GCase), are the most penetrant common genetic risk factor for PD and dementia with Lewy bodies, and also associate with faster disease progression. To explore the mechanism by which mutations in GBA influence pathogenesis of these diseases, we previously created a Drosophila model of GBA deficiency (Gba1b) that manifests neurodegeneration, motor and cognitive deficits, and accelerated protein aggregation. Proteomic analysis of Gba1b mutants revealed dysregulation of proteins involved in extracellular vesicle (EV) biology, and we found altered protein composition of EVs from Gba1b mutants. To further investigate this novel mechanism, we hypothesized that GBA may influence the spread of pathogenic protein aggregates throughout the brain via EVs. We found that protein aggregation is reduced cell-autonomously and non-cell-autonomously by expressing wildtype GCase in specific tissues. In particular, accumulation of insoluble ubiquitinated proteins and Ref(2)P in the brains of Gba1b flies are reduced by ectopic expression of GCase in muscle tissue. Neuronal expression of GCase also cell-autonomously rescued protein aggregation in brain as well as non-cell-autonomously rescued protein aggregation in muscle. Muscle-specific GBA expression rescued the elevated levels of EV-intrinsic proteins and Ref(2)P found in EVs from Gba1b flies. Genetically perturbing EV biogenesis in specific tissues in the absence of GCase revealed differential cell-autonomous effects on protein aggregation but could not replicate the non-cell-autonomous rescue observed with tissue-specific GBA expression. Additionally, we identified ectopically expressed GCase within isolated EVs. Together, our findings suggest that GCase deficiency mediates accelerated spread of protein aggregates between cells and tissues via dysregulated EVs, and EV-mediated trafficking of GCase may partially account for the reduction in aggregate spread.Author’s SummaryParkinson’s disease (PD) is a common neurodegenerative disease characterized by abnormal clumps of proteins (aggregates) within the brain and other tissues which can lead to cellular dysfunction and death. Mutations in the gene GBA, which encodes glucocerebrosidase (GCase), are the strongest genetic risk factor for PD, and are associated with faster disease progression. GCase-deficient mutant flies display features suggestive of PD including increased protein aggregation in brain and muscle. We found that restoring GCase protein in the muscle of mutant flies reduced protein aggregation in muscle and the brain, suggesting a mechanism involving interaction between tissues. Previous work indicated that GBA influences extracellular vesicles (EVs) – small membrane-bound structures released by cells to communicate and/or transport cargo from cell to cell. Here, we found increased aggregated proteins within EVs of mutant flies, which was reduced by restoring GCase in muscle. In addition, we found GCase within the EVs, possibly explaining how GCase in one tissue such as muscle could reduce protein aggregation in a distant tissue like the brain. Our findings suggest that GCase influences proteins within EVs, affecting the spread of protein aggregation. This may be important to understanding PD progression and could uncover new targets to slow neurodegeneration.

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IRE1 promotes neurodegeneration through autophagy-dependent neuron death in the Drosophila model of Parkinson’s disease

Cell Death and Disease ◽

10.1038/s41419-019-2039-6 ◽

2019 ◽

Vol 10 (11) ◽

Cited By ~ 3

Author(s):

Cheng Yan ◽

Jingqi Liu ◽

Jiamei Gao ◽

Ying Sun ◽

Lei Zhang ◽

...

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Er Stress ◽

Cell Fate ◽

Neuronal Cell ◽

Dependent Manner ◽

Neuron Death ◽

Locomotor Impairment ◽

Photoreceptor Neurons

Abstract Abnormal aggregation of misfolded pathological proteins in neurons is a prominent feature of neurodegenerative disorders including Parkinson’s disease (PD). Perturbations of proteostasis at the endoplasmic reticulum (ER) triggers ER stress, activating the unfolded protein response (UPR). Chronic ER stress is thought to underlie the death of neurons during the neurodegenerative progression, but the precise mechanism by which the UPR pathways regulate neuronal cell fate remains incompletely understood. Here we report a critical neurodegenerative role for inositol-requiring enzyme 1 (IRE1), the evolutionarily conserved ER stress sensor, in a Drosophila model of PD. We found that IRE1 was hyperactivated upon accumulation of α-synuclein in the fly photoreceptor neurons. Ectopic overexpression of IRE1 was sufficient to trigger autophagy-dependent neuron death in an XBP1-independent, JNK-dependent manner. Furthermore, IRE1 was able to promote dopaminergic neuron loss, progressive locomotor impairment, and shorter lifespan, whereas blocking IRE1 or ATG7 expression remarkably ameliorated the progression of α-synuclein-caused Parkinson’s disease. These results provide in vivo evidence demonstrating that the IRE1 pathway drives PD progression through coupling ER stress to autophagy-dependent neuron death.

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AnIn VivoMicrodialysis Study of FLZ Penetration through the Blood-Brain Barrier in Normal and 6-Hydroxydopamine Induced Parkinson’s Disease Model Rats

BioMed Research International ◽

10.1155/2014/850493 ◽

2014 ◽

Vol 2014 ◽

pp. 1-11 ◽

Cited By ~ 6

Author(s):

Jinfeng Hou ◽

Qian Liu ◽

Yingfei Li ◽

Hua Sun ◽

Jinlan Zhang

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Disease Model ◽

Time Curve ◽

Liquid Chromatography Tandem Mass ◽

Bbb Permeability ◽

6 Hydroxydopamine ◽

The Brain ◽

Active Substances

FLZ (N-[2-(4-hydroxy-phenyl)-ethyl]-2-(2,5-dimethoxy-phenyl)-3-(3-methoxy-4-hydroxy-phenyl)-acrylamide) is a novel synthetic squamosamide derivative and a potential anti-Parkinson’s disease (PD) agent. The objective of the present study was to investigate the penetration of free FLZ across the BBB and the effects of P-gp inhibition on FLZ transport in normal and 6-hydroxydopamine (6-OHDA) induced PD model rats.In vivomicrodialysis was used to collect FLZ containing brain and blood dialysates following intravenous (i.v.) drug administration either with or without pretreatment with the specific P-gp inhibitor, zosuquidar trihydrochloride (zosuquidar·3HCl). A sensitive, rapid, and reliable ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) technique was developed and validated to quantitate free FLZ levels in the dialysates. No significant differences were observed in the brain/blood FLZ area under the concentration-time curve (AUC) ratio between normal and PD model rats. However, pretreatment with zosuquidar·3HCl markedly increased the AUC ratio in both rat models. In addition, FLZ penetration was similar in zosuquidar·3HCl-pretreated normal and PD rats. These results suggest that P-gp inhibition increases BBB permeability to FLZ, thereby supporting the hypothesis that P-gp normally restricts FLZ transfer to the brain. These findings could provide reference data for future clinical trials and may aid investigation of the BBB permeability of other CNS-active substances.

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Nurr1:RXRα heterodimer activation as monotherapy for Parkinson’s disease

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1616874114 ◽

2017 ◽

Vol 114 (15) ◽

pp. 3999-4004 ◽

Cited By ~ 24

Author(s):

Athanasios D. Spathis ◽

Xenophon Asvos ◽

Despina Ziavra ◽

Theodoros Karampelas ◽

Stavros Topouzis ◽

...

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Neurodegenerative Disorder ◽

Therapeutic Potential ◽

Induced Pluripotent Stem Cell ◽

Symptomatic Improvement ◽

Acid Decarboxylase ◽

Dependent Manner ◽

Amino Acid Decarboxylase

Parkinson’s disease (PD) is a progressive neurodegenerative disorder characterized by the loss of dopaminergic (DAergic) neurons in the substantia nigra and the gradual depletion of dopamine (DA). Current treatments replenish the DA deficit and improve symptoms but induce dyskinesias over time, and neuroprotective therapies are nonexistent. Here we report that Nuclear receptor-related 1 (Nurr1):Retinoid X receptor α (RXRα) activation has a double therapeutic potential for PD, offering both neuroprotective and symptomatic improvement. We designed BRF110, a unique in vivo active Nurr1:RXRα-selective lead molecule, which prevents DAergic neuron demise and striatal DAergic denervation in vivo against PD-causing toxins in a Nurr1-dependent manner. BRF110 also protects against PD-related genetic mutations in patient induced pluripotent stem cell (iPSC)-derived DAergic neurons and a genetic mouse PD model. Remarkably, besides neuroprotection, BRF110 up-regulates tyrosine hydroxylase (TH), aromatic l-amino acid decarboxylase (AADC), and GTP cyclohydrolase I (GCH1) transcription; increases striatal DA in vivo; and has symptomatic efficacy in two postneurodegeneration PD models, without inducing dyskinesias on chronic daily treatment. The combined neuroprotective and symptomatic effects of BRF110 identify Nurr1:RXRα activation as a potential monotherapeutic approach for PD.

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Protein Deimination Signatures in Plasma and Plasma-EVs and Protein Deimination in the Brain Vasculature in a Rat Model of Pre-Motor Parkinson’s Disease

International Journal of Molecular Sciences ◽

10.3390/ijms21082743 ◽

2020 ◽

Vol 21 (8) ◽

pp. 2743 ◽

Cited By ~ 5

Author(s):

Marco Sancandi ◽

Pinar Uysal-Onganer ◽

Igor Kraev ◽

Audrey Mercer ◽

Sigrun Lange

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Rat Model ◽

Lupus Erythematosus ◽

Biomarker Discovery ◽

Alcoholic Fatty Liver ◽

Brain Vasculature ◽

Micro Rnas ◽

The Brain

The identification of biomarkers for early diagnosis of Parkinson’s disease (PD) is of pivotal importance for improving approaches for clinical intervention. The use of translatable animal models of pre-motor PD therefore offers optimal opportunities for novel biomarker discovery in vivo. Peptidylarginine deiminases (PADs) are a family of calcium-activated enzymes that contribute to protein misfolding through post-translational deimination of arginine to citrulline. Furthermore, PADs are an active regulator of extracellular vesicle (EV) release. Both protein deimination and extracellular vesicles (EVs) are gaining increased attention in relation to neurodegenerative diseases, including in PD, while roles in pre-motor PD have yet to be investigated. The current study aimed at identifying protein candidates of deimination in plasma and plasma-EVs in a rat model of pre-motor PD, to assess putative contributions of such post-translational changes in the early stages of disease. EV-cargo was further assessed for deiminated proteins as well as three key micro-RNAs known to contribute to inflammation and hypoxia (miR21, miR155, and miR210) and also associated with PD. Overall, there was a significant increase in circulating plasma EVs in the PD model compared with sham animals and inflammatory and hypoxia related microRNAs were significantly increased in plasma-EVs of the pre-motor PD model. A significantly higher number of protein candidates were deiminated in the pre-motor PD model plasma and plasma-EVs, compared with those in the sham animals. KEGG (Kyoto encyclopedia of genes and genomes) pathways identified for deiminated proteins in the pre-motor PD model were linked to “Alzheimer’s disease”, “PD”, “Huntington’s disease”, “prion diseases”, as well as for “oxidative phosphorylation”, “thermogenesis”, “metabolic pathways”, “Staphylococcus aureus infection”, gap junction, “platelet activation”, “apelin signalling”, “retrograde endocannabinoid signalling”, “systemic lupus erythematosus”, and “non-alcoholic fatty liver disease”. Furthermore, PD brains showed significantly increased staining for total deiminated proteins in the brain vasculature in cortex and hippocampus, as well as increased immunodetection of deiminated histone H3 in dentate gyrus and cortex. Our findings identify EVs and post-translational protein deimination as novel biomarkers in early pre-motor stages of PD.

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Systemic α-synuclein injection triggers selective neuronal pathology as seen in patients with Parkinson’s disease

Molecular Psychiatry ◽

10.1038/s41380-019-0608-9 ◽

2019 ◽

Cited By ~ 3

Author(s):

Wei-Li Kuan ◽

Katherine Stott ◽

Xiaoling He ◽

Tobias C. Wood ◽

Sujeong Yang ◽

...

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Brain Regions ◽

Neuronal Populations ◽

Novel Approach ◽

Quaternary Structures ◽

Cellular Pathology ◽

First Time ◽

The Brain ◽

Delivery Approach

AbstractParkinson’s disease (PD) is an α-synucleinopathy characterized by the progressive loss of specific neuronal populations. Here, we develop a novel approach to transvascularly deliver proteins of complex quaternary structures, including α-synuclein preformed fibrils (pff). We show that a single systemic administration of α-synuclein pff triggers pathological transformation of endogenous α-synuclein in non-transgenic rats, which leads to neurodegeneration in discrete brain regions. Specifically, pff-exposed animals displayed a progressive deterioration in gastrointestinal and olfactory functions, which corresponded with the presence of cellular pathology in the central and enteric nervous systems. The α-synuclein pathology generated was both time dependent and region specific. Interestingly, the most significant neuropathological changes were observed in those brain regions affected in the early stages of PD. Our data therefore demonstrate for the first time that a single, transvascular administration of α-synuclein pff can lead to selective regional neuropathology resembling the premotor stage of idiopathic PD. Furthermore, this novel delivery approach could also be used to deliver a range of other pathogenic, as well as therapeutic, protein cargos transvascularly to the brain.

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