scholarly journals Brain atrophy progression in Parkinson's disease is shaped by connectivity and local vulnerability

2021 ◽  
Author(s):  
Christina Tremblay ◽  
Shady Rahayel ◽  
Andrew Vo ◽  
Filip Morys ◽  
Golia Shafiei ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Brain Atrophy ◽  
De Novo ◽  
Brain Connectivity ◽  
Brain Regions ◽  
Posterior Cingulate Cortex ◽  
Alpha Synuclein ◽  
Cell Type ◽  
Expression Of Genes

Atrophy in multiple brain regions has been reported in the early stages of Parkinson's Disease, but there have been few longitudinal studies. How intrinsic properties of the brain, such as anatomical connectivity, local cell type distribution and gene expression combine to determine the pattern of disease progression remains unknown. One hypothesis proposes that the disease stems from prion-like propagation of misfolded alpha-synuclein via the connectome that might cause varying degrees of tissue damage based on local properties. Here we used MRI data from the Parkinson Progression Markers Initiative to test this model by mapping the progression of brain atrophy over one, two and four years and relating it to brain structural and functional connectivity, cell type expression and gene ontology enrichment analyses. In this longitudinal study, we derived atrophy progression maps for the three time points using deformation-based morphometry applied to T1-weighted MRI from 74 de novo Parkinson's Disease patients (50 Men: 24 Women) and 157 healthy control participants (115 Men: 42 Women). After regressing out the expected age and sex effects associated with normal aging, we found that atrophy significantly progressed over two and four years in the caudate, nucleus accumbens, hippocampus, and the temporal, parietal, occipital and posterior cingulate cortex. This progression was shaped by both structural and functional brain connectivity. Also, the progression of atrophy was more pronounced in regions with a higher expression of genes related to synapses and was related to the prevalence of oligodendrocytes and endothelial cells. In sum, we demonstrate that the progression of atrophy in Parkinson's Disease is in line with the prion-like propagation hypothesis of alpha-synuclein and provide evidence that synapses may be especially vulnerable to synucleinopathy. In addition to identifying vulnerable brain regions, this study reveals different factors that may be implicated in the neurotoxic mechanisms leading to progression in Parkinson's Disease.

scholarly journals The Prion-Like Spreading of Alpha-Synuclein in Parkinson’s Disease: Update on Models and Hypotheses

2021 ◽  
Vol 22 (15) ◽  
pp. 8338
Author(s):  
Asad Jan ◽  
Nádia Pereira Gonçalves ◽  
Christian Bjerggaard Vaegter ◽  
Poul Henning Jensen ◽  
Nelson Ferreira
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Molecular Mechanisms ◽  
De Novo ◽  
Alpha Synuclein ◽  
Experimental Models ◽  
Cellular Factors ◽  
Recent Developments ◽  
Novel Targets ◽  
Presynaptic Protein

The pathological aggregation of the presynaptic protein α-synuclein (α-syn) and propagation through synaptically coupled neuroanatomical tracts is increasingly thought to underlie the pathophysiological progression of Parkinson’s disease (PD) and related synucleinopathies. Although the precise molecular mechanisms responsible for the spreading of pathological α-syn accumulation in the CNS are not fully understood, growing evidence suggests that de novo α-syn misfolding and/or neuronal internalization of aggregated α-syn facilitates conformational templating of endogenous α-syn monomers in a mechanism reminiscent of prions. A refined understanding of the biochemical and cellular factors mediating the pathological neuron-to-neuron propagation of misfolded α-syn will potentially elucidate the etiology of PD and unravel novel targets for therapeutic intervention. Here, we discuss recent developments on the hypothesis regarding trans-synaptic propagation of α-syn pathology in the context of neuronal vulnerability and highlight the potential utility of novel experimental models of synucleinopathies.

Cortical Thinning Associated with Age and CSF Biomarkers in Early Parkinson’s Disease Is Modified by the SNCA rs356181 Polymorphism

2018 ◽  
Vol 18 (5-6) ◽  
pp. 233-238
Author(s):  
Frederic Sampedro ◽  
Juan Marín-Lahoz ◽  
Saul Martínez-Horta ◽  
Javier Pagonabarraga ◽  
Jaime Kulisevsky
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Cognitive Decline ◽  
De Novo ◽  
Brain Regions ◽  
Cortical Atrophy ◽  
Csf Biomarkers ◽  
Gene Encoding ◽  
Cortical Thinning ◽  
Age Related

The role of cerebrospinal fluid (CSF) biomarkers such as CSF α-synuclein and CSF tau in predicting cognitive decline in Parkinson’s disease (PD) continues to be inconsistent. Here, using a cohort of de novo PD patients with preserved cognition from the Parkinson’s Progression Markers Initiative (PPMI), we show that the SNCA rs356181 single nucleotide polymorphism (SNP) modulates the effect of these CSF biomarkers on cortical thinning. Depending on this SNP’s genotype, cortical atrophy was associated with either higher or lower CSF biomarker levels. Additionally, this SNP modified age-related atrophy. Importantly, the integrity of the brain regions where this phenomenon was observed correlated with cognitive measures. These results suggest that this genetic variation of the gene encoding the α-synuclein protein, known to be involved in the development of PD, also interferes in its subsequent neurodegeneration. Overall, our findings could shed light on the so far incongruent association of common CSF biomarkers with cognitive decline in PD.

scholarly journals Directed brain connectivity identifies widespread functional network changes in Parkinson’s disease

2021 ◽  
Author(s):  
Mite Mijalkov ◽  
Giovanni Volpe ◽  
Joana B. Pereira
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Large Scale ◽  
Neurodegenerative Disorder ◽  
Brain Connectivity ◽  
Brain Regions ◽  
New Method ◽  
Functional Network ◽  
Whole Brain ◽  
Functional Brain Networks

AbstractParkinson’s disease (PD) is a progressive neurodegenerative disorder characterized by topological changes in large-scale functional brain networks. These networks are commonly analysed using undirected correlations between the activation signals of brain regions. However, this approach suffers from an important drawback: it assumes that brain regions get activated at the same time, despite previous evidence showing that brain activation features causality, with signals being typically generated in one region and then propagated to other ones. Thus, in order to address this limitation, in this study we developed a new method to assess whole-brain directed functional connectivity in patients with PD and healthy controls using anti-symmetric delayed correlations, which capture better this underlying causality. To test the potential of this new method, we compared it to standard connectivity analyses based on undirected correlations. Our results show that whole-brain directed connectivity identifies widespread changes in the functional networks of PD patients compared to controls, in contrast to undirected methods. These changes are characterized by increased global efficiency, clustering and transitivity as well as lower modularity. In addition, changes in the directed connectivity patterns in the precuneus, thalamus and superior frontal gyrus were associated with motor, executive and memory deficits in PD patients. Altogether, these findings suggest that directional brain connectivity is more sensitive to functional network changes occurring in PD compared to standard methods. This opens new opportunities for the analysis of brain connectivity and the development of new brain connectivity markers to track PD progression.

scholarly journals Single Cell Atlas of Human Putamen Reveals Disease Specific Changes in Synucleinopathies: Parkinson's Disease and Multiple System Atrophy

2021 ◽  
Author(s):  
Rahul Pande ◽  
Yinyin Huang ◽  
Erin Teeple ◽  
Pooja Joshi ◽  
Amilcar Flores-Morales ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Multiple System Atrophy ◽  
Single Cell ◽  
Alpha Synuclein ◽  
Cell Type ◽  
Distinct Cell Type ◽  
Altered Expression ◽  
Cell Type Specific ◽  
Disease Specific

Understanding disease biology at a cellular level from disease specific tissues is imperative for effective drug development for complex neurodegenerative diseases. We profiled 87,086 nuclei from putamen tissue of healthy controls, Parkinson's Disease (PD), and Multiple System Atrophy (MSA) subjects to construct a comprehensive single cell atlas. Although both PD and MSA are manifestations of alpha-synuclein protein aggregation, we observed that both the diseases have distinct cell-type specific changes. We see a possible expansion and activation of microglia and astrocytes in PD compared to MSA and controls. Contrary to PD microglia, we found absence of upregulated unfolded protein response in MSA microglia compared to controls. Differentially expressed genes in major cell types are enriched for genes associated with PD-GWAS loci. We found altered expression of major neurodegeneration associated genes, SNCA, MAPT, LRRK2, and APP, at cell-type resolution. We also identified disease associated gene modules using a network biology approach. Overall, this study creates an interactive atlas from synucleinopathies and provides major cell-type specific disease insights.

Effects of dopaminergic depletion and brain atrophy on neuropsychiatric symptoms in de novo Parkinson’s disease

2017 ◽  
Vol 89 (2) ◽  
pp. 197-204 ◽  
Author(s):  
Byoung Seok Ye ◽  
Seun Jeon ◽  
Sohoon Yoon ◽  
Seong Woo Kang ◽  
KyoungWon Baik ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Brain Atrophy ◽  
Negative Binomial ◽  
De Novo ◽  
Neuropsychiatric Symptoms ◽  
Brain Mri ◽  
Negative Binomial Regression ◽  
Cortical Thinning ◽  
Positron Emission

BackgroundNeuropsychiatric symptoms impact the patients’ quality of life and caregivers’ burdens in Parkinson’s disease (PD). We aimed to investigate the effects of striatal dopaminergic depletion and brain atrophy on the neuropsychiatric symptoms of patients with PD.MethodsTwo hundred and seven patients with de novo drug-naïve PD underwent dopamine transporter (DAT) positron emission tomography and brain MRI scanning. In addition, the patients were assessed with caregiver-administered neuropsychiatric inventory (NPI) questionnaires. To evaluate the effects of DAT uptake, subcortical volume and cortical thinning on the patients’ neuropsychiatric symptoms, we performed logistic regression and negative binomial regression analyses on the NPI data after controlling for possible confounders.ResultsFrontal cortical thinning was associated with the presence of nighttime behaviour and irritability, and the thinning correlated with the severity of the nighttime behaviour. Temporal cortical thinning was associated with the presence of aggression/agitation, and it correlated with the severity of the aggression/agitation. Subcortical atrophy in the accumbens was associated with the presence of disinhibition and correlated with the severity of the disinhibition. Putamen atrophy and insular thinning were independently associated with the presence of apathy, but only insular thinning correlated with the severity of the apathy. Of the predictors, only frontal cortical thinning correlated with the total NPI score.ConclusionsThe results of this study suggested that accumbens atrophy and frontotemporal cortical thinning, especially frontal cortical thinning, independently contributed to neuropsychiatric symptoms in patients with PD, while DAT uptake did not affect the neuropsychiatric symptoms.

scholarly journals Integration of functional genomics data to uncover cell type-specific pathways affected in Parkinson's disease

2021 ◽  
Author(s):  
Viola Volpato
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Neurodegenerative Disorder ◽  
Disease Risk ◽  
Late Onset ◽  
Alpha Synuclein ◽  
Biological Information ◽  
Cell Type ◽  
Risk Variants ◽  
Cell Type Specific

Parkinson's disease (PD) is the second most prevalent late-onset neurodegenerative disorder worldwide after Alzheimer's disease for which available drugs only deliver temporary symptomatic relief. Loss of dopaminergic neurons (DaNs) in the substantia nigra and intracellular alpha-synuclein inclusions are the main hallmarks of the disease but the events that cause this degeneration remain uncertain. Despite cell types other than DaNs such as astrocytes, microglia and oligodendrocytes have been recently associated with the pathogenesis of PD, we still lack an in-depth characterisation of PD-affected brain regions at cell-type resolution that could help our understanding of the disease mechanisms. Nevertheless, publicly available large-scale brain-specific genomic, transcriptomic and epigenomic datasets can be further exploited to extract different layers of cell type-specific biological information for the reconstruction of cell type-specific transcriptional regulatory networks. By intersecting disease risk variants within the networks, it may be possible to study the functional role of these risk variants and their combined effects at cell type- and pathway levels, that, in turn, can facilitate the identification of key regulators involved in disease progression, which are often potential therapeutic targets.

scholarly journals Neurodegeneration and neuroinflammation are linked, but independent of α-synuclein inclusions, in a seeding/spreading mouse model of Parkinson’s disease

2020 ◽  
Author(s):  
Pierre Garcia ◽  
Wiebke Jürgens-Wemheuer ◽  
Oihane Uriarte ◽  
Kristopher J Schmit ◽  
Annette Masuch ◽  
...  
Keyword(s):  
Gene Expression ◽  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Gene Expression Profiling ◽  
Expression Profiling ◽  
Active Role ◽  
Brain Regions ◽  
Alpha Synuclein ◽  
Intracerebral Injection ◽  
Inclusion Formation

AbstractA key process of neurodegeneration in Parkinson’s disease (PD) is the transneuronal spreading of α-synuclein. Alpha-synuclein is a presynaptic protein that is implicated in the pathogenesis of PD and other synucleinopathies, where it forms, upon intracellular aggregation, pathological inclusions. Other hallmarks of PD include neurodegeneration and microgliosis in susceptible brain regions. Whether it is primarily transneuronal spreading of α-synuclein particles, inclusion formation, or other mechanisms, such as inflammation, that cause neurodegeneration in PD is unclear. We used spreading/aggregation of α-synuclein induced by intracerebral injection of α-synuclein preformed fibrils into the mouse brain to address this question. We performed quantitative histological analysis for α-synuclein inclusions, neurodegeneration, and microgliosis in different brain regions, and a gene expression profiling of the ventral midbrain, at two different timepoints after disease induction. We observed significant neurodegeneration and microgliosis in brain regions not only with, but also without α-synuclein inclusions. We also observed prominent microgliosis in injured brain regions that did not correlate with neurodegeneration nor with inclusion load. In longitudinal gene expression profiling experiments, we observed early and unique alterations linked to microglial mediated inflammation that preceded neurodegeneration, indicating an active role of microglia in inducing neurodegeneration. Our observations indicate that α-synuclein inclusion formation is not the major driver in the early phases of PD-like neurodegeneration, but that diffusible, oligomeric α-synuclein species, which induce unusual microglial reactivity, play a key role in this process. Our findings uncover new features of α-synuclein induced pathologies, in particular microgliosis, and point to the necessity of a broader view of the process of “prion-like spreading” of that protein.

scholarly journals High diagnostic performance of independent alpha-synuclein seed amplification assays for detection of early Parkinson’s disease

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Marco J. Russo ◽  
Christina D. Orru ◽  
Luis Concha-Marambio ◽  
Simone Giaisi ◽  
Bradley R. Groveman ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Clinical Diagnosis ◽  
Diagnostic Performance ◽  
De Novo ◽  
Alpha Synuclein ◽  
Diagnostic Tools ◽  
Dat Spect ◽  
Progression Markers ◽  
Early Parkinson’S Disease

AbstractAlpha-synuclein seed amplification assays (αSyn-SAAs) are promising diagnostic tools for Parkinson’s disease (PD) and related synucleinopathies. They enable detection of seeding-competent alpha-synuclein aggregates in living patients and have shown high diagnostic accuracy in several PD and other synucleinopathy patient cohorts. However, there has been confusion about αSyn-SAAs for their methodology, nomenclature, and relative accuracies when performed by various laboratories. We compared αSyn-SAA results obtained from three independent laboratories to evaluate reproducibility across methodological variations. We utilized the Parkinson’s Progression Markers Initiative (PPMI) cohort, with DATSCAN data available for comparison, since clinical diagnosis of early de novo PD is critical for neuroprotective trials, which often use dopamine transporter imaging to enrich their cohorts. Blinded cerebrospinal fluid (CSF) samples for a randomly selected subset of PPMI subjects (30 PD, 30 HC, and 20 SWEDD), from both baseline and year 3 collections for the PD and HC groups (140 total CSF samples) were analyzed in parallel by each lab according to their own established and optimized αSyn-SAA protocols. The αSyn-SAA results were remarkably similar across laboratories, displaying high diagnostic performance (sensitivity ranging from 86 to 96% and specificity from 93 to 100%). The assays were also concordant for samples with results that differed from clinical diagnosis, including 2 PD patients determined to be clinically inconsistent with PD at later time points. All three assays also detected 2 SWEDD subjects as αSyn-SAA positive who later developed PD with abnormal DAT-SPECT. These multi-laboratory results confirm the reproducibility and value of αSyn-SAA as diagnostic tools, illustrate reproducibility of the assay in expert hands, and suggest that αSyn-SAA has potential to provide earlier diagnosis with comparable or superior accuracy to existing methods.

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