| 1. |
- Killinger, Bryan A., et al.
(author)
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The vermiform appendix impacts the risk of developing Parkinson’s disease
- 2018
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In: Science Translational Medicine. - : American Association for the Advancement of Science (AAAS). - 1946-6234 .- 1946-6242. ; 10:465
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Journal article (peer-reviewed)abstract
- The pathogenesis of Parkinson’s disease (PD) involves the accumulation of aggregated -synuclein, which has been suggested to begin in the gastrointestinal tract. Here, we determined the capacity of the appendix to modify PD risk and influence pathogenesis. In two independent epidemiological datasets, involving more than 1.6 million individuals and over 91 million person-years, we observed that removal of the appendix decades before PD onset was associated with a lower risk for PD, particularly for individuals living in rural areas, and delayed the age of PD onset. We also found that the healthy human appendix contained intraneuronal -synuclein aggregates and an abundance of PD pathology–associated -synuclein truncation products that are known to accumulate in Lewy bodies, the pathological hallmark of PD. Lysates of human appendix tissue induced the rapid cleavage and oligo-merization of full-length recombinant -synuclein. Together, we propose that the normal human appendix contains pathogenic forms of -synuclein that affect the risk of developing PD.
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| 2. |
- Ventorp, Filip, et al.
(author)
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Exendin-4 Treatment Improves LPS-Induced Depressive-Like Behavior Without Affecting ProInflammatory Cytokines
- 2017
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In: Journal of Parkinson's Disease. - : IOS Press. - 1877-7171 .- 1877-718X. ; 7:2, s. 263-273
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Journal article (peer-reviewed)abstract
- Background: Exendin-4 is a peptide agonist of the glucagon-like peptide-1 (GLP-1) receptor, currently in clinical trials as a potential disease-modifying therapy for Parkinson's disease. In light of this, it is important to understand potential modes of action of exendin-4 in the brain. Exendin-4 is neuroprotective and has been proposed to be directly anti-inflammatory, and that this is one way it reduces neurodegeneration. However, prior studies have focused on animal models involving both neurodegeneration and inflammation, therefore, it is also possible that the observed decreased inflammation is secondary to reduced neurodegeneration. Objective: To investigate whether exendin-4 directly reduces inflammation in the brain following an insult that involves neuroinflammation but not neurodegeneration, namely systemic administration of lipopolysaccharide (LPS). Methods: Rats were administered LPS systemically and were treated with either 0.5 mu g/kg exendin-4 or saline vehicle injections over 5 days. Behavior was evaluated with forced swim test. We assayed TNF-alpha and IL-1 beta levels in cerebrospinal fluid and cytokine mRNA expression in striatal, hippocampal and cortical tissues using qPCR. We determined brain monoamines using high-performance liquid chromatography. Finally, we isolated primary brain microglia from rats and measured cytokine production after exendin-4 treatment and LPS stimulation. Results: Exendin-4 treatment did not affect cytokine mRNA expression in brain, cytokine levels in cerebrospinal fluid or cytokine production from cultured microglia, although there was a trend towards increased striatal dopamine. Importantly, exendin-4 significantly prevented depressive-like behavior at 24 hours after LPS injection, indicating that the drug engaged a target in the brain. Depressive-like behavior was associated with altered dopamine turnover in the striatum. Conclusion: We did not detect any anti-inflammatory effects of exendin-4. In previous studies exploring the effects of exendin-4 on brain insults involving neurodegeneration, observations of reduced inflammation might have been secondary to mitigation of neuronal death. Our results indicate that the effects of exendin-4 on behavior may be due to effects on dopamine synthesis or metabolism.
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| 3. |
- Ventorp, Filip, et al.
(author)
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The CD44 ligand hyaluronic acid is elevated in the cerebrospinal fluid of suicide attempters and is associated with increased blood-brain barrier permeability.
- 2016
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In: Journal of Affective Disorders. - : Elsevier BV. - 1573-2517 .- 0165-0327. ; 193, s. 349-354
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Journal article (peer-reviewed)abstract
- The glycosaminoglycan hyaluronic acid (HA) is an important component of the extracellular matrix (ECM) in the brain. CD44 is a cell adhesion molecule that binds to HA in the ECM and is present on astrocytes, microglia and certain neurons. Cell adhesion molecules have been reported to be involved in anxiety and mood disorders. CD44 levels are decreased in the cerebrospinal fluid (CSF) of depressed individuals, and the CD44 gene has been identified in brain GWAS studies as a possible risk gene for suicidal behavior.
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| 4. |
- Barker, Roger A, et al.
(author)
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Are Stem Cell-Based Therapies for Parkinson's Disease Ready for the Clinic in 2016?
- 2016
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In: Journal of Parkinson's Disease. - 1877-718X. ; 6:1, s. 57-63
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Journal article (peer-reviewed)abstract
- Recent news of an impending clinical cell transplantation trial in Parkinson's disease using parthenogenetic stem cells as a source of donor tissue have raised hopes in the patient community and sparked discussion in the research community. Based on discussions held by a global collaborative initiative on translation of stem cell therapy in Parkinson's disease, we have identified a set of key questions that we believe should be addressed ahead of every clinical stem cell-based transplantation trial in this disorder. In this article, we first provide a short history of cell therapy in Parkinson's disease and briefly describe the current state-of-art regarding human stem cell-derived dopamine neurons for use in any patient trial. With this background information as a foundation, we then discuss each of the key questions in relation to the upcoming therapeutic trial and critically assess if the time is ripe for clinical translation of parthenogenetic stem cell technology in Parkinson's disease.
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| 5. |
- Grey, Marie, et al.
(author)
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Acceleration of α-synuclein aggregation by exosomes
- 2015
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In: Journal of Biological Chemistry. - 1083-351X. ; 290:5, s. 2969-2982
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Journal article (peer-reviewed)abstract
- Exosomes are small vesicles released from cells into extra-cellular space. We have isolated exosomes from neuroblastoma cells and investigated their influence on the aggregation of α-synuclein, a protein associated with Parkinson disease pathology. Using cryo-transmission electron microscopy of exosomes we found spherical unilamellar vesicles with a significant protein content, and Western blot analysis revealed that they contain, as expected, the proteins flotillin-1 and alix. Using thioflavin T fluorescence to monitor aggregation kinetics, we found that exosomes catalyze the process in a similar manner as low concentration of preformed α-synuclein fibrils. The exosomes reduce the lag time indicating that they provide catalytic environments for nucleation. The catalytic effect of exosomes derived from naive cells and cells that over-express α-synuclein do not differ. Vesicles prepared from extracted exosome lipids accelerate aggregation, suggesting that the lipids in exosomes are sufficient for the catalytic effect to arise. Using mass spectrometry we found several phospholipid classes in the exosomes, including phosphatidyl choline, phosphatidyl serine, phosphatidyl ethanolamine, phosphatidyl inositol and the gangliosides GM2 and GM3. Within each class, several species with different acyl chains were identified. We then prepared vesicles from corresponding pure lipids or defined mixtures, most of which were found to retard α-synuclein aggregation. As a striking exception, vesicles containing ganglioside lipids GM1 or GM3 accelerate the process. Understanding how α-synuclein interacts with biological membranes to promote neurological disease might lead to the identification of novel therapeutic targets.
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| 6. |
- Kurowska, Zuzanna, et al.
(author)
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Identification of Multiple QTLs Linked to Neuropathology in the Engrailed-1 Heterozygous Mouse Model of Parkinson's Disease
- 2016
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In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 6
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Journal article (peer-reviewed)abstract
- Motor symptoms in Parkinson's disease are attributed to degeneration of midbrain dopaminergic neurons (DNs). Heterozygosity for Engrailed-1 (En1), one of the key factors for programming and maintenance of DNs, results in a parkinsonian phenotype featuring progressive degeneration of DNs in substantia nigra pars compacta (SNpc), decreased striatal dopamine levels and swellings of nigro-striatal axons in the SwissOF1-En1+/- mouse strain. In contrast, C57Bl/6-En1+/- mice do not display this neurodegenerative phenotype, suggesting that susceptibility to En1 heterozygosity is genetically regulated. Our goal was to identify quantitative trait loci (QTLs) that regulate the susceptibility to PD-like neurodegenerative changes in response to loss of one En1 allele. We intercrossed SwissOF1-En1+/- and C57Bl/6 mice to obtain F2 mice with mixed genomes and analyzed number of DNs in SNpc and striatal axonal swellings in 120 F2-En1+/- 17 week-old male mice. Linkage analyses revealed 8 QTLs linked to number of DNs (p = 2.4e-09, variance explained = 74%), 7 QTLs linked to load of axonal swellings (p = 1.7e-12, variance explained = 80%) and 8 QTLs linked to size of axonal swellings (p = 7.0e-11, variance explained = 74%). These loci should be of prime interest for studies of susceptibility to Parkinson's disease-like damage in rodent disease models and considered in clinical association studies in PD.
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| 7. |
- Lamberts, Jennifer T, et al.
(author)
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Spreading of α-synuclein in the face of axonal transport deficits in Parkinson's disease: A speculative synthesis.
- 2015
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In: Neurobiology of Disease. - : Elsevier BV. - 0969-9961. ; 77:Jul 15, s. 276-283
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Research review (peer-reviewed)abstract
- Parkinson's disease (PD) is mainly attributed to degeneration of dopamine neurons in the substantia nigra, but its etiopathogenesis also includes impaired protein clearance and axonal transport dysfunction, among others. The spread of α-synuclein (α-syn) aggregates from one neuron to another, in a prion-like manner, is hypothesized to contribute to PD progression. Axonal transport is likely to play a crucial role in this movement of α-syn aggregates between brain regions. At the same time, deficits in axonal transport are suggested to contribute to neuronal failure in PD. In this review, we discuss the apparent contradiction that axonal transport might be essential for disease progression, while dysfunction of axonal transport could simultaneously be a cornerstone of PD pathogenesis. We speculate around models that reconcile how axonal transport can play such a paradoxical role.
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| 8. |
- LI, WEN, et al.
(author)
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Extensive graft-derived dopaminergic innervation is maintained 24 years after transplantation in the degenerating parkinsonian brain.
- 2016
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In: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 1091-6490. ; 113:23, s. 6544-6549
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Journal article (peer-reviewed)abstract
- Clinical trials using cells derived from embryonic ventral mesencephalon have shown that transplanted dopaminergic neurons can survive and function in the long term, as demonstrated by in vivo brain imaging using 18F-fluorodopa and 11C-raclopride positron emission tomography. Here we report the postmortem analysis of a patient with Parkinson’s disease who 24 y earlier underwent unilateral transplantation of embryonic dopaminergic neurons in the putamen and subsequently exhibited major motor improvement and recovery of striatal dopaminergic function. Histopathological analysis showed that a dense, near-normal graft-derived dopaminergic reinnervation of the putamen can be maintained for a quarter of a century despite severe host brain pathology and with no evidence of immune response. In addition, ubiquitin- and α-synuclein–positive inclusions were seen, some with the appearance of typical Lewy bodies, in 11–12% of the grafted dopaminergic neurons, reflecting the spread of pathology from the host brain to the transplants. Because the clinical benefits induced by transplantation in this patient were gradually lost after 14 y posttransplantation, our findings provide the first reported evidence, to our knowledge, that even a viable dopaminergic graft giving rise to extensive striatal reinnervation may lose its efficacy if widespread degenerative changes develop in the host brain.
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| 9. |
- Nordström, Ulrika, et al.
(author)
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Progressive nigrostriatal terminal dysfunction and degeneration in the engrailed1 heterozygous mouse model of Parkinson's disease.
- 2015
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In: Neurobiology of Disease. - : Elsevier BV. - 0969-9961. ; 73, s. 70-82
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Journal article (peer-reviewed)abstract
- Current research on Parkinson's disease (PD) pathogenesis requires relevant animal models that mimic the gradual and progressive development of neuronal dysfunction and degeneration that characterizes the disease. Polymorphisms in engrailed 1 (En1), a homeobox transcription factor that is crucial for both the development and survival of mesencephalic dopaminergic neurons, are associated with sporadic PD. This suggests that En1 mutant mice might be a promising candidate PD model. Indeed, a mouse that lacks one En1 allele exhibits decreased mitochondrial complex I activity and progressive midbrain dopamine neuron degeneration in adulthood, both features associated with PD. We aimed to further characterize the disease-like phenotype of these En1(+/-) mice with a focus on early neurodegenerative changes that can be utilized to score efficacy of future disease modifying studies. We observed early terminal defects in the dopaminergic nigrostriatal pathway in En1(+/-) mice. Several weeks before a significant loss of dopaminergic neurons in the substantia nigra could be detected, we found that striatal terminals expressing high levels of dopaminergic neuron markers TH, VMAT2, and DAT were dystrophic and swollen. Using transmission electron microscopy, we identified electron dense bodies consistent with abnormal autophagic vacuoles in these terminal swellings. In line with these findings, we detected an up-regulation of the mTOR pathway, concurrent with a downregulation of the autophagic marker LC3B, in ventral midbrain and nigral dopaminergic neurons of the En1(+/-) mice. This supports the notion that autophagic protein degradation is reduced in the absence of one En1 allele. We imaged the nigrostriatal pathway using the CLARITY technique and observed many fragmented axons in the medial forebrain bundle of the En1(+/-) mice, consistent with axonal maintenance failure. Using in vivo electrochemistry, we found that nigrostriatal terminals in the dorsal striatum were severely deficient in dopamine release and reuptake. Our findings support a progressive retrograde degeneration of En1(+/-) nigrostriatal neurons, akin to what is suggested to occur in PD. We suggest that using the En1(+/-) mice as a model will provide further key insights into PD pathogenesis, and propose that axon terminal integrity and function can be utilized to estimate dopaminergic neuron health and efficacy of experimental PD therapies.
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| 10. |
- Reyes, Juan F, et al.
(author)
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A cell culture model for monitoring α-synuclein cell-to-cell transfer.
- 2015
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In: Neurobiology of Disease. - : Elsevier BV. - 0969-9961. ; 77:Jul 16, s. 266-275
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Journal article (peer-reviewed)abstract
- The transfer of α-synuclein (α-syn) between cells has been proposed to be the primary mechanism of disease spreading in Parkinson's disease. Several cellular models exist that monitor the uptake of recombinant α-syn from the culture medium. Here we established a more physiologically relevant model system in which α-syn is produced and transferred between mammalian neurons. We generated cell lines expressing either α-syn tagged with fluorescent proteins or fluorescent tags alone then we co-cultured these cell lines to measure protein uptake. We used live-cell imaging to demonstrate intercellular α-syn transfer and used flow cytometry and high content analysis to quantify the transfer. We then successfully inhibited intercellular protein transfer genetically by down-regulating dynamin or pharmacologically using dynasore or heparin. In addition, we differentiated human induced pluripotent stem cells carrying a triplication of the α-syn gene into dopaminergic neurons. These cells secreted high levels of α-syn, which was taken up by neighboring neurons. Collectively, our co-culture systems provide simple but physiologically relevant tools for the identification of genetic modifiers or small molecules that inhibit α-syn cell-to-cell transfer.
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