Different neurotoxicity and seeding activity between α-synuclein oligomers formed in plasma of patients with Parkinson's disease and multiple system atrophy.

Previous studies have shown that α-synuclein (α-Syn) aggregates derived from the brains of patients with Parkinson's disease (PD) and multiple system atrophy (MSA) exhibit different phosphorylation, cytotoxicity, and seeding activity. However, the mechanism underlying the differences remains poorly understood. Here, recombinant human α-Syn was incubated in the plasma of patients with PD and MSA, and the oligomers formed in the plasma (PD-O-α-Syn and MSA-O-α-Syn) were purified and analyzed for their phosphorylation, cytotoxicity and seeding activity. In vitro assays revealed that both PD-O-α-Syn and MSA-O-α-Syn were phosphorylated at serine 129. However, the phosphorylation degree of MSA-O-α-Syn was significantly higher than that of PD-O-α-Syn. In addition, MSA-O-α-Syn exhibited stronger cytotoxicity and seeding activity compared with PD-O-α-Syn. In vivo experiments showed that mice receiving intrastriatal inoculation of MSA-O-α-Syn developed more severe motor dysfunction and dopaminergic degeneration than mice receiving intrastriatal inoculation of PD-O-α-Syn. Compared with the mice inoculated with PD-O-α-Syn, the mice inoculated with MSA-O-α-Syn accumulated more phosphorylated and oligomerized α-Syn in the striatum and brain regions (substantia nigra, hippocampus and prefrontal cortex) away from the inoculated site. The results obtained suggest that α-Syn oligomers formed in PD and MSA plasma are different in phosphorylation, cytotoxicity, and seeding activity.

DNA methylation patterns in the frontal lobe white matter of multiple system atrophy, Parkinson's disease, and progressive supranuclear palsy: a cross-comparative investigation.

Multiple system atrophy (MSA) is a rare neurodegenerative disease characterized by neuronal loss and gliosis, with oligodendroglial cytoplasmic inclusions (GCIs) containing α-synuclein being the primary pathological hallmark. Clinical presentations of MSA overlap with other parkinsonian disorders, such as Parkinson's disease (PD), dementia with Lewy bodies (DLB), and progressive supranuclear palsy (PSP), posing challenges in early diagnosis. Numerous studies have reported alterations in DNA methylation in neurodegenerative diseases, with candidate loci being identified in various parkinsonian disorders including MSA, PD, and PSP. Although MSA and PSP present with substantial white matter pathology, alterations in white matter have also been reported in PD. However, studies comparing the DNA methylation architectures of white matter in these diseases are lacking. We therefore aimed to investigate genome-wide DNA methylation patterns in the frontal lobe white matter of individuals with MSA (n = 17), PD (n = 17), and PSP (n = 16) along with controls (n = 15) using the Illumina EPIC array, to identify shared and disease-specific DNA methylation alterations. Genome-wide DNA methylation profiling of frontal lobe white matter in the three parkinsonian disorders revealed substantial commonalities in DNA methylation alterations in MSA, PD, and PSP. We further used weighted gene correlation network analysis to identify disease-associated co-methylation signatures and identified dysregulation in processes relating to Wnt signaling, signal transduction, endoplasmic reticulum stress, mitochondrial processes, RNA interference, and endosomal transport to be shared between these parkinsonian disorders. Our overall analysis points toward more similarities in DNA methylation patterns between MSA and PD, both synucleinopathies, compared to that between MSA and PD with PSP, which is a tauopathy. Our results also highlight several shared DNA methylation changes and pathways indicative of converging molecular mechanisms in the white matter contributing toward neurodegeneration in all three parkinsonian disorders.

The Pathobiology of Behavioral Changes in Multiple System Atrophy: An Update.

While cognitive impairment, which was previously considered a red flag against the clinical diagnosis of multiple system atrophy (MSA), is a common symptom of this rare neurodegenerative disorder, behavioral disorders are reported in 30 to 70% of MSA patients. They include anxiety, apathy, impaired attention, compulsive and REM sleep behavior disorders (RBD), and these conditions, like depression, are early and pervasive features in MSA, which may contribute to disease progression. Despite changing concepts of behavioral changes in this synucleinopathy, the underlying pathophysiological and biochemical mechanisms are poorly understood. While specific neuropathological data are unavailable, neuroimaging studies related anxiety disorders to changes in the cortico-limbic system, apathy (and depression) to dysfunction of prefrontal-subcortical circuits, and compulsive behaviors to impairment of basal ganglia networks and involvement of orbito-frontal circuits. Anxiety has also been related to α-synuclein (αSyn) pathology in the amygdala, RBD to striatal monoaminergic deficit, and compulsive behavior in response to dopamine agonist therapy in MSA, while the basic mechanisms of the other behavioral disorders and their relations to other non-motor dysfunctions in MSA are unknown. In view of the scarcity of functional and biochemical findings in MSA with behavioral symptoms, further neuroimaging and biochemical studies are warranted in order to obtain better insight into their pathogenesis as a basis for the development of diagnostic biomarkers and future adequate treatment modalities of these debilitating comorbidities.

Association of dysphagia severity in multiple system atrophy with the specific binding ratio on dopamine transporter SPECT.

OBJECTIVE: Dysphagia in multiple system atrophy (MSA) is life-threatening and is caused by parkinsonism with cerebellar ataxia as a contributing factor. The present study investigated the relationship between dysphagia severity in MSA and the specific binding ratio (SBR) on dopamine transporter (DaT) SPECT using the Hyodo score, a qualitative scale for use with fiberoptic endoscopic evaluation of swallowing (FEES). METHODS: Hyodo score's ability to predict aspiration during a FEES examination of 88 patients with MSA was first tested. Then the clinical characteristics, Hyodo score, and SBR of patients with either predominant parkinsonism (MSA-P; n = 11) or cerebellar ataxia (MSA-C; n = 25) who underwent FEES and DaT SPECT simultaneously were compared. RESULTS: Logistic regression demonstrated that the Hyodo score was a significant predictive factor of aspiration (p = 0.003). The MSA-P group had a significantly higher Hyodo score (p = 0.026) and lower SBR (p = 0.011) than the MSA-C group while neither group demonstrated any significant difference in disease duration at the FEES examination. Linear regression demonstrated a significant, inverse correlation between the Hyodo score and SBR in the MSA-P (p = 0.044; r = -0.616) and MSA-C (p = 0.044; r = -0.406) groups. When the effect of SBR was removed by analysis of covariance, no significant difference in the Hyodo score remained between the groups. CONCLUSIONS: Our results suggested an association between presynaptic changes in nigrostriatal dopaminergic neurons and dysphagia severity in MSA which largely contributes to the difference in dysphagia severity between MSA-P and MSA-C.

[Two patients of immunotherapy-responsive autoimmune cerebellar ataxia fulfilled with criteria of multiple system atrophy].

We report two patients with autoimmune cerebellar ataxia who fulfilled the diagnostic criteria of multiple system atrophy (MSA) and responded to immunotherapies. Patient 1 was a 72-year-old man who was diagnosed with clinically probable MSA according to Movement Disorder Society criteria. Patient 2 was a 68-year-old man who was diagnosed with clinically established MSA according to Movement Disorder Society criteria. Both patients showed cerebellar ataxia, autonomic dysfunction, and pyramidal tract signs; however, they also had atypical clinical features. Patient 1 exhibited self-|limiting mild improvement of clinical symptoms and had inflammatory findings in his cerebrospinal fluid. Patient 2 showed a rapidly progressive clinical course. We therefore examined anti-neuronal antibodies using tissue-based immunohistochemical assays with frozen rat cerebellum sections. We detected autoantibodies that mainly reacted with the cytoplasm of Purkinje cells. The two patients then underwent immunotherapies, which led to substantial improvements in their clinical symptoms. Our findings indicate that some patients with autoimmune cerebella ataxia have clinical features that resemble MSA, and respond well to immunotherapies.

Orexin and Sleep Disturbances in Alpha-Synucleinopathies: a Systematic Review.

PURPOSE OF REVIEW: Sleep disturbances are amongst most frequent non-motor symptoms of Parkinson's Disease (PD), and they are similarly frequently reported in other alpha-syncleinopathies, such as Dementia with Lewy Bodies (DLB) and Multiple System Atrophy (MSA). More recently, the orexin system has been implicated in control of arousal based on salient environmental set points, and its dysregulation in sleep issues in alpha-synucleinopathies suggested by the findings from the translational animal models. However, its role in the patients with alpha-synucleinopathies remains unclear. We thus set to systematically review, and to critically assess, contemporary evidence on the association of the orexinergic system and sleep disturbances in alpha-synucleinopathies. In this systematic review, studies investigating orexin and sleep in alpha-synucleinopathies (Rapid Eye Movement (REM) Behaviour Disorder (RBD), Parkinson's Disease (PD), Dementia with Lewy Bodies (DLB), Multiple System Atrophy (MSA)) were identified using electronic database searches of PubMed, Web of Science and PsychINFO using MeSH terms, keywords, and title words such as "Alpha-synucleinopathies" AND "Orexin" AND "Sleep Disturbances". RECENT FINDINGS: 17 studies were included in this systemic review, of which 2 studies on RBD, 10 on PD, 4 on DLB, and 1 on MSA patients. Taken together, RBD and PD studies suggest a potential adaptive increase in orexin levels in early stages of the neurodegenerative process, with reduced levels more often reported for later, more advanced stages of illness. To date, no differences in orexin levels were demonstrated between MSA patients and healthy controls. There is a dearth of studies on the role of orexin levels in alpha-synucleinopathies. Moreover, significant methodologic limitations in the current body of work, including use of non-standardised research protocols and lack of prospective, multi-centre studies, disallow for any finite conclusion in regards to underlying pathomechanisms. Nonetheless, a picture of a complex, multifaceted relationship between the dysregulation of the orexinergic pathway and sleep disturbances in alpha-synucleinopathies is emerging. Hence, future studies disentangling orexinergic pathomechanisms of alpha-syncleinopathies are urgently needed to obtain a more comprehensive account of the role of orexinergic pathway in alpha-synucleinopathies. Pharmacological manipulations of orexins may have multiple therapeutic applications in treatment strategies, disease diagnosis, and might be effective for treating both motor and non-motor symptoms.

Clinical Application of 18 F-THK5351 PET to Image Ongoing Astrogliosis in MSA-P and MSA-C.

ABSTRACT: 18 F-labeled THK5351 PET can visualize ongoing astrogliosis by estimating monoamine oxidase B levels and can be used as an adjunct for diagnosing neurodegenerative disorders. Little has been reported on multiple system atrophy (MSA) in the differential diagnosis of parkinsonian syndromes. Here, we present 18 F-THK5351 images in typical cases of MSA-P (parkinsonian type) and MSA-C (cerebellar type), showing intense 18 F-THK5351 uptake in the lateral-posterior part of the putamen (MSA-P) and in the pons and middle cerebellar peduncles (MSA-C). Hence, this study illustrates the possible utility of 18 F-THK5351 PET as an adjunct for diagnosing MSA-P and MSA-C by imaging ongoing astrogliosis.

Differential diagnosis value of sympathetic skin response and cutaneous silent period on early-stage multiple system atrophy and Parkinson disease.

PURPOSE: Early differentiation between Parkinson's disease (PD) and Multiple system atrophy (MSA), particularly the parkinsonian subtypes (MSA-P), is challenging due to similar clinical symptoms. We aimed to evaluate Sympathetic skin response (SSR) and Cutaneous silent period (CSP) parameters in patients with MSA-P and PD to identify possible biomarkers that could distinguish the two groups of patients in early stage. METHODS: 22 individuals with early-stage MSA-P, 29 with early-stage PD, and 28 healthy controls were recruited from Guangdong Provincial People's Hospital. Demographic data was collected for all participants. Their SSR and CSP were evaluated using clinical electromyography equipment. Data were compared between different groups. The diagnostic accuracy of SSR and CSP parameters was calculated using the ROC curve. Logistic regression was used to produce an integration model to enhance diagnostic utility. RESULTS: Foot amplitude, CSP end latency and duration distinguished MSA-P from PD with the area under the curve (AUC) 0.770, 0.806, and 0.776, respectively. Foot and hand SSR amplitude distinguished PD from HC with the AUC 0.871 and 0.768, respectively. Foot SSR amplitude, hand SSR amplitude, and CSP end latency distinguished MSA-P from HC with the AUC 0.964, 0.872, and 0.812, respectively. The combination of SSR and CSP parameters differentiation between MSA-P and PD, PD and HC with the AUC 0.829 and 0.879, respectively. CONCLUSIONS: Analysis of SSR and CSP parameters showed excellent diagnostic accuracy in discriminating patients with early-stage MSA-P from HC and good diagnostic accuracy in discriminating patients with MSA-P from PD with early stages.

Data-Driven Subtypes of Multiple System Atrophy and Their Implications for Prognosis.

Background: While multiple system atrophy (MSA) presents with high heterogeneous motor and nonmotor symptoms, the associations between clinical phenotypes and prognosis are unclear. Objective: We aimed to evaluate clinical phenotypes of MSA using data-driven approach and measure the impact of phenotypes on survival and bedbound status. Methods: 193 MSA patients were recruited from Xuanwu Hospital Capital Medical University, whose history, motor and non-motor symptoms were examined using cluster analysis. Ninety-five participants were followed-up via telephone after a mean of 31.87 months. We employed Kaplan- Meier analysis to examine survival and performed Cox and logistic regression analyses to identify factors associated with survival and bedbound status. Results: We identified four clinical profiles of MSA: cerebellar symptom-dominant, sleep and mood disorder-dominant, rigid akinetic-dominant, and malignant diffuse. The overall median survival was 7.75 years (95% CI 7.19-8.31). After adjusting for years from symptom onset to diagnosis, age and sex, patients in the malignant diffuse and rigid akinetic-dominant clusters had greater risk of death than sleep and mood disorder-dominant cluster. Furthermore, patients in the malignant diffuse and rigid akinetic-dominant clusters had higher risk of being bedbound than cerebellar symptom-dominant cluster. Conclusions: The malignant diffuse and sleep and mood disorder-dominant were identified besides the two classical subtypes, parkinsonism, and cerebellar symptom-variant. Patients with rigid-akinetic motor profiles have a worse prognosis than cerebellar symptom-dominant profiles in general. Diffuse symptoms, especially postural instability, and cognitive alterations at diagnosis, indicate rapid functional loss and disease progression. The different profiles and prognoses might indicate varied underlying pathological mechanisms.

Multiple system atrophy (MSA) is a complex disease that can affect both movement and non-movement functions of patients. However, we do not know much about how these different symptoms relate to how the patient's health might change over time. In this study, we looked at 193 MSA patients to learn more about if the patients can be distinguished into different subgroups at diagnosis and if the subgroups might be associated with their survival and ability to move in the future. We found four main subgroups of patients: group 1 characterized by the dysfunction of cerebellum (a part of the brain), group 2 characterized by sleep and mood problems, group 3 characterized by rigidity and slow movements, and group 4 with diffuse symptoms mentioned above. After tracking 95 patients for nearly 32 months, we found that those characterized by rigidity and slow movements, and those with diffuse symptoms had a higher chance of dying compared to those characterized by sleep and mood problems. Group 3 and 4 also had a higher chance of becoming unable to move out of bed. This suggests that patients with severe symptoms of rigidity and slowness at diagnosis tend to have a worse outlook than those without. And if multiple MSA symptoms are found when the patient is diagnosed, especially trouble with thinking, are also signs that the disease is getting worse quickly. By understanding these disease patterns, we can better tailor treatments and provide better support for people with MSA.

The recovery of sympathetic skin responses with levodopa in a patient with multiple system atrophy-parkinsonian type.

Herein, we report a 62-year-old female patient with Multiple system atrophy (MSA) at whom the sympathetic skin responses (SSRs) were absent at initial investigations. However, the levodopa therapy provided normalization of SSRs and moderately improvement in orthostatic hypotension-related symptoms. Based on this rare illustration, we discuss the possible mechanisms underlying the pathophysiology of autonomic dysfunction in MSA. We remark on the need for future clinical and experimental studies in this field.

A rapidly progressive multiple system atrophy-cerebellar variant model presenting marked glial reactions with inflammation and spreading of α-synuclein oligomers and phosphorylated α-synuclein aggregates.

Multiple system atrophy (MSA) is a severe α-synucleinopathy facilitated by glial reactions; the cerebellar variant (MSA-C) preferentially involves olivopontocerebellar fibres with conspicuous demyelination. A lack of aggressive models that preferentially involve olivopontocerebellar tracts in adulthood has hindered our understanding of the mechanisms of demyelination and neuroaxonal loss, and thus the development of effective treatments for MSA. We therefore aimed to develop a rapidly progressive mouse model that recaptures MSA-C pathology. We crossed Plp1-tTA and tetO-SNCA*A53T mice to generate Plp1-tTA::tetO-SNCA*A53T bi-transgenic mice, in which human A53T α-synuclein-a mutant protein with enhanced aggregability-was specifically produced in the oligodendrocytes of adult mice using Tet-Off regulation. These bi-transgenic mice expressed mutant α-synuclein from 8 weeks of age, when doxycycline was removed from the diet. All bi-transgenic mice presented rapidly progressive motor deterioration, with wide-based ataxic gait around 22 weeks of age and death around 30 weeks of age. They also had prominent demyelination in the brainstem/cerebellum. Double immunostaining demonstrated that myelin basic protein was markedly decreased in areas in which SM132, an axonal marker, was relatively preserved. Demyelinating lesions exhibited marked ionised calcium-binding adaptor molecule 1-, arginase-1-, and toll-like receptor 2-positive microglial reactivity and glial fibrillary acidic protein-positive astrocytic reactivity. Microarray analysis revealed a strong inflammatory response and cytokine/chemokine production in bi-transgenic mice. Neuronal nuclei-positive neuronal loss and patchy microtubule-associated protein 2-positive dendritic loss became prominent at 30 weeks of age. However, a perceived decrease in tyrosine hydroxylase-positive neurons in the substantia nigra pars compacta in bi-transgenic mice compared with wild-type mice was not significant, even at 30 weeks of age. Wild-type, Plp1-tTA, and tetO-SNCA*A53T mice developed neither motor deficits nor demyelination. In bi-transgenic mice, double immunostaining revealed human α-synuclein accumulation in neurite outgrowth inhibitor A (Nogo-A)-positive oligodendrocytes beginning at 9 weeks of age; its expression was further increased at 10 to 12 weeks, and these increased levels were maintained at 12, 24, and 30 weeks. In an α-synuclein-proximity ligation assay, α-synuclein oligomers first appeared in brainstem oligodendrocytes as early as 9 weeks of age; they then spread to astrocytes, neuropil, and neurons at 12 and 16 weeks of age. α-Synuclein oligomers in the brainstem neuropil were most abundant at 16 weeks of age and decreased thereafter; however, those in Purkinje cells successively increased until 30 weeks of age. Double immunostaining revealed the presence of phosphorylated α-synuclein in Nogo-A-positive oligodendrocytes in the brainstem/cerebellum as early as 9 weeks of age. In quantitative assessments, phosphorylated α-synuclein gradually and successively accumulated at 12, 24, and 30 weeks in bi-transgenic mice. By contrast, no phosphorylated α-synuclein was detected in wild-type, tetO-SNCA*A53T, or Plp1-tTA mice at any age examined. Pronounced demyelination and tubulin polymerisation, promoting protein-positive oligodendrocytic loss, was closely associated with phosphorylated α-synuclein aggregates at 24 and 30 weeks of age. Early inhibition of mutant α-synuclein expression by doxycycline diet at 23 weeks led to fully recovered demyelination; inhibition at 27 weeks led to persistent demyelination with glial reactions, despite resolving phosphorylated α-synuclein aggregates. In conclusion, our bi-transgenic mice exhibited progressively increasing demyelination and neuroaxonal loss in the brainstem/cerebellum, with rapidly progressive motor deterioration in adulthood. These mice showed marked microglial and astrocytic reactions with inflammation that was closely associated with phosphorylated α-synuclein aggregates. These features closely mimic human MSA-C pathology. Notably, our model is the first to suggest that α-synuclein oligomers may spread from oligodendrocytes to neurons in transgenic mice with human α-synuclein expression in oligodendrocytes. This model of MSA is therefore particularly useful for elucidating the in vivo mechanisms of α-synuclein spreading from glia to neurons, and for developing therapies that target glial reactions and/or α-synuclein oligomer spreading and aggregate formation in MSA.

SNCA and TPPP transcripts increase in oligodendroglial cytoplasmic inclusions in multiple system atrophy.

Multiple system atrophy (MSA) is characterized by glial cytoplasmic inclusions (GCIs) containing aggregated α-synuclein (α-syn) in oligodendrocytes. The origin of α-syn accumulation in GCIs is unclear, in particular whether abnormal α-syn aggregates result from the abnormal elevation of endogenous α-syn expression in MSA or ingested from the neuronal source. Tubulin polymerization promoting protein (TPPP) has been reported to play a crucial role in developing GCI pathology. Here, the total cell body, nucleus, and cytoplasmic area density of SNCA and TPPP transcripts in neurons and oligodendrocytes with and without various α-syn pathologies in the pontine base in autopsy cases of MSA (n = 4) and controls (n = 2) were evaluated using RNAscope with immunofluorescence. Single-nucleus RNA-sequencing data for TPPP was evaluated using control frontal cortex (n = 3). SNCA and TPPP transcripts were present in the nucleus and cytoplasm of oligodendrocytes in both controls and diseased, with higher area density in GCIs and glial nuclear inclusions in MSA. Area densities of SNCA and TPPP transcripts were lower in neurons showing cytoplasmic inclusions in MSA. Indeed, TPPP transcripts were unexpectedly found in neurons, while the anti-TPPP antibody failed to detect immunoreactivity. Single-nucleus RNA-sequencing revealed significant TPPP transcript expression predominantly in oligodendrocytes, but also in excitatory and inhibitory neurons. This study addressed the unclear origin of accumulated α-syn in GCIs, proposing that the elevation of SNCA transcripts may supply templates for misfolded α-syn. In addition, the parallel behavior of TPPP and SNCA transcripts in GCI development highlights their potential synergistic contribution to inclusion formation. In conclusion, this study advances our understanding of MSA pathogenesis, offers insights into the dynamics of SNCA and TPPP transcripts in inclusion formation, and proposes regulating their transcripts for future molecular therapy to MSA.

An update on multiple system atrophy.

PURPOSE OF REVIEW: Multiple system atrophy (MSA) is a rapidly progressive synucleinopathy characterized by autonomic failure, parkinsonism, and cerebellar ataxia. Here, we provide an update on α-synuclein's role in MSA pathophysiology and review the new Movement Disorders Society (MDS) diagnostic criteria and the utility of α-synuclein-based biomarkers. We also highlight ongoing efforts toward clinical trial readiness and review potential disease-modifying therapies undergoing clinical trials. RECENT FINDINGS: A role of urinary tract infections in triggering α-synuclein aggregation and contribution of genes implicated in oligodendroglial development have been suggested in the MSA pathophysiology. The clinically probable MSA category of the new diagnostic criteria shows improved accuracy in early disease stages. Predictors of phenoconversion from pure autonomic failure to MSA are now better defined. Alpha-synuclein strains in CSF and serum, phosphorylated α-synuclein deposits in the skin, and brain α-synuclein pathology visualized using PET ligand [18F]ACI-12589 are emerging as valuable diagnostic tools. Clinical trials in MSA investigate drugs targeting α-synuclein aggregation or preventing α-synuclein expression, along with stem cell and gene therapies to halt disease progression. SUMMARY: New MSA diagnostic criteria and α-synuclein-based biomarkers may enhance diagnostic accuracy while promising therapies are in development to address disease progression.

A multiverse of α-synuclein: investigation of prion strain properties with carboxyl-terminal truncation specific antibodies in animal models.

Synucleinopathies are a group of neurodegenerative disorders characterized by the presence of misfolded α-Synuclein (αSyn) in the brain. These conditions manifest with diverse clinical and pathophysiological characteristics. This disease diversity is hypothesized to be driven by αSyn strains with differing biophysical properties, potentially influencing prion-type propagation and consequentially the progression of illness. Previously, we investigated this hypothesis by injecting brain lysate (seeds) from deceased individuals with various synucleinopathies or human recombinant αSyn preformed fibrils (PFFs) into transgenic mice overexpressing either wild type or A53T human αSyn. In the studies herein, we expanded on these experiments, utilizing a panel of antibodies specific for the major carboxyl-terminally truncated forms of αSyn (αSynΔC). These modified forms of αSyn are found enriched in human disease brains to inform on potential strain-specific proteolytic patterns. With monoclonal antibodies specific for human αSyn cleaved at residues 103, 114, 122, 125, and 129, we demonstrate that multiple system atrophy (MSA) seeds and PFFs induce differing neuroanatomical spread of αSyn pathology associated with host specific profiles. Overall, αSyn cleaved at residue 103 was most widely present in the induced pathological inclusions. Furthermore, αSynΔC-positive inclusions were present in astrocytes, but more frequently in activated microglia, with patterns dependent on host and inoculum. These findings support the hypothesis that synucleinopathy heterogeneity might stem from αSyn strains with unique biochemical properties that include proteolytic processing, which could result in dominant strain properties.

Aptamer binding footprints discriminate α-synuclein fibrillar polymorphs from different synucleinopathies.

Synucleinopathies, including dementia with Lewy bodies (DLB), Parkinson's disease (PD), and multiple system atrophy (MSA), are characterized by the presence of α-synuclein (α-syn) aggregates in the central nervous system. Recent evidence suggests that the heterogeneity of synucleinopathies may be partly explained by the fact that patients may have different α-syn fibrillar polymorphs with structural differences. In this study, we identify nuclease resistant 2'fluoro-pyrimidine RNA aptamers that can differentially bind to structurally distinct α-syn fibrillar polymorphs. Moreover, we introduce a method, AptaFOOT-Seq, designed to rapidly assess the affinity of a mixture of these aptamers for different α-SYN fibrillar polymorphs using next-generation sequencing. Our findings reveal that the binding behavior of aptamers can be very different when they are tested separately or in the presence of other aptamers. In this case, competition and cooperation can occur, providing a higher level of information, which can be exploited to obtain specific 'footprints' for different α-Syn fibrillar polymorphs. Notably, these footprints can distinguish polymorphs obtained from patients with PD, DLB or MSA. This result suggests that aptaFOOT-Seq could be used for the detection of misfolded or abnormal protein conformations to improve the diagnosis of synucleinopathies.

Computer-Based Evaluation of α-Synuclein Pathology in Multiple System Atrophy as a Novel Tool to Recognize Disease Subtypes.

Multiple system atrophy (MSA) is a neurodegenerative disorder with variable disease course and distinct constellations of clinical (cerebellar [MSA-C] or parkinsonism [MSA-P]) and pathological phenotypes, suggestive of distinct α-synuclein (αSyn) strains. Neuropathologically, MSA is characterized by the accumulation of αSyn in oligodendrocytic glial cytoplasmic inclusions (GCI). Using a novel computer-based method, this study quantified the size of GCIs, density of all αSyn pathology, density of only the GCIs, and number of GCIs in MSA cases (n = 20). The putamen and cerebellar white matter were immunostained with the disease-associated 5G4 anti-αSyn antibody. Following digital scanning and image processing, total 5G4-immunoreactive pathology (ie, neuronal, neuritic, and glial) and GCIs were optically dissected for inclusion size and density measurement and then evaluated applying a novel computer-based method using ImageJ. GCI size varied between cases and brain regions (P < .0001), and heterogeneity in the density of all αSyn pathology including the density and number of GCIs were observed between regions and across cases, where MSA-C cases had a significantly higher density of all αSyn pathology in the cerebellar white matter (P = .049). Some region-specific morphologic variables inversely correlated with the age of onset and death, suggestive of an underlying aging-related cellular mechanism. Unsupervised K-means cluster analysis classified MSA cases into 3 distinct groups based on region-specific morphologic variables. In conclusion, we developed a novel computer-based method that is easily accessible, providing a first step to developing artificial intelligence-based evaluation strategies for large scale comparative studies. Our observations on the variability of morphologic variables between brain regions and cases highlight (1) the importance of computer-based approaches to detect features not considered in the routine diagnostic practice, and (2) novel aspects for the identification of previously unrecognized MSA subtypes that do not necessarily reflect the current clinical classification of MSA-C or MSA-P.

The characteristic and biomarker value of transcranial sonography in cerebellar ataxia.

OBJECTIVE: Transcranial sonography (TCS) is a noninvasive neuroimaging technique, visualizing deep brain structures and the ventricular system. Although widely employed in diagnosing various movement disorders, such as Parkinson's disease and dystonia, by detecting disease-specific abnormalities, the specific characteristics of the TCS in cerebellar ataxia remain inconclusive. We aimed to assess the potential value of TCS in patients with cerebellar ataxias for disease diagnosis and severity assessment. METHODS: TCS on patients with genetic and acquired cerebellar ataxia, including 94 with spinocerebellar ataxias (SCAs) containing 10 asymptomatic carriers, 95 with cerebellar subtype of multiple system atrophy (MSA-C), and 100 healthy controls (HC), was conducted. Assessments included third ventricle width, substantia nigra (SN) and lentiform nucleus (LN) echogenicity, along with comprehensive clinical evaluations and genetic testing. RESULTS: The study revealed significant TCS abnormalities in patients with cerebellar ataxia, such as enlarged third ventricle widths and elevated rates of hyperechogenic SN and LN. TCS showed high accuracy in distinguishing patients with SCA or MSA-C from HC, with an AUC of 0.870 and 0.931, respectively. TCS abnormalities aided in identifying asymptomatic SCA carriers, effectively differentiating them from HC, with an AUC of 0.725. Furthermore, third ventricle width was significantly correlated with SARA and ICARS scores in patients with SCA3 and SCOPA-AUT scores in patients with MSA-C. The SN area and SARA or ICARS scores in patients with SCA3 were also positively correlated. INTERPRETATION: Our findings illustrate remarkable TCS abnormalities in patients with cerebellar ataxia, serving as potential biomarkers for clinical diagnosis and progression assessment.

Usefulness of Olfactory Bulb Measurement in 3D-FIESTA in Differentiating Parkinson Disease from Atypical Parkinsonism.

BACKGROUND AND PURPOSE: Parkinson disease is a prevalent disease, with olfactory dysfunction recognized as an early nonmotor manifestation. It is sometimes difficult to differentiate Parkinson disease from atypical parkinsonism using conventional MR imaging and motor symptoms. It is also known that olfactory loss occurs to a lesser extent or is absent in atypical parkinsonism. To the best of our knowledge, no study has examined olfactory bulb changes to differentiate Parkinson disease from atypical parkinsonism, even in an early diagnosis, and its association with conventional MR imaging findings. Hence, we aimed to assess the utility of olfactory bulb measurements in differentiating Parkinson disease from atypical parkinsonism even in the early stage. MATERIALS AND METHODS: In this retrospective study, we enrolled 108 patients with Parkinson disease, 13 with corticobasal syndrome, 15 with multiple system atrophy, and 17 with progressive supranuclear palsy who developed parkinsonism. Thirty-nine age-matched healthy subjects served as controls. All subjects underwent conventional MR imaging and 3D FIESTA for olfactory bulb measurements using manual ROI quantification of the cross-sectional olfactory bulb area using the coronal plane. Bilateral olfactory bulb measurements were averaged. For group comparisons, we used the Welch t test, and we assessed diagnostic accuracy using receiver operating characteristic analysis. RESULTS: Patients with Parkinson disease had a mean olfactory bulb area of 4.2 (SD, 1.0 mm2), significantly smaller than in age-matched healthy subjects (6.6 [SD, 1.7 mm2], P < .001), and those with corticobasal syndrome (5.4 [SD, 1.2 mm2], P < .001), multiple system atrophy (6.5 [SD, 1.2 mm2], P < .001), and progressive supranuclear palsy (5.4 [SD, 1.2 mm2], P < .001). The receiver operating characteristic analysis for the olfactory bulb area measurements showed good diagnostic performance in differentiating Parkinson disease from atypical parkinsonism, with an area under the curve of 0.87, an optimal cutoff value of 5.1 mm2, and a false-positive rate of 18%. When we compared within 2 years of symptom onset, the olfactory bulb in Parkinson disease (4.2 [SD, 1.1 mm2]) remained significantly smaller than in atypical parkinsonism (versus corticobasal syndrome (6.1 [SD, 0.7 mm2]), P < .001; multiple system atrophy (6.3 [SD, 1.4 mm2]), P < .001; and progressive supranuclear palsy (5.2 [1.3 mm2], P = .003, respectively). CONCLUSIONS: 3D FIESTA-based olfactory bulb measurement holds promise for distinguishing Parkinson disease from atypical parkinsonism, especially in the early stage.