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Background: Brain network dysfunction has been characterized by resting-state electroencephalography (EEG) and magnetic resonance imaging (MRI) in the prodromal stage. This study aimed to identify multi-modal electrophysiological and neuroimaging biomarkers for differential diagnosis in synucleinopathies and phenoconversion in isolated rapid eye movement sleep behavior disorder (iRBD). Methods: We enrolled 35 patients with multiple system atrophy (MSA), 32 with Parkinson's disease (PD), 30 with iRBD and 30 matched healthy controls (HC). Power spectral density (PSD) was calculated in different frequency bands. EEG functional connectivity (FC) was calculated using the weighted Phase Lag Index (wPLI) after source localization. Significant network disruptions were further confirmed by MRI FC analysis. Results: Quantitative EEG analysis demonstrated that delta and theta power spectral density significantly differed among MSA, PD and HC. The increased PSD was correlated with cognitive decline and olfactory dysfunction in PD. Band-specific FC profiles were observed in theta, alpha, and gamma bands. The hypoconnected alpha network significantly correlated with motor dysfunction, while the gamma FC distinguished PD from MSA. By integrating EEG and MRI network analyses, we found that FC between the olfactory cortex and dorsolateral prefrontal cortex was significantly different between MSA and PD. A multimodal discriminative model for MSA and PD, integrating spectral and FC attributes of EEG and MRI, yielded an area under the receiver operating characteristic curve of 0.900. Simultaneously, we found the FC abnormalities were more prominent than spectral features in iRBD indicating prodromal dysfunction. The decreased FC between the angular gyrus and striatum was identified in α-synucleinopathies. This hypoconnectivity was associated with dopaminergic degeneration in iRBD examined by dopamine transporter imaging. Discussion: Our study demonstrated EEG spectral and functional profiles in prodromal and clinical-defined synucleinopathies. Multimodal EEG and MRI provided a novel approach to discriminate MSA and PD, and monitor neurodegenerative progression in the preclinical phase.

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A presynaptic protein called α-synuclein plays a crucial role in synaptic function and neurotransmitter release. However, its misfolding and aggregation have been implicated in a variety of neurodegenerative diseases, particularly Parkinson's disease, dementia with Lewy bodies, and multiple system atrophy. Emerging evidence suggests that α-synuclein interacts with various cellular pathways, including mitochondrial dysfunction, oxidative stress, and neuroinflammation, which contributes to neuronal cell death. Moreover, α-synuclein has been involved in the propagation of neurodegenerative processes through prion-like mechanisms, where misfolded proteins induce similar conformational changes in neighboring neurons. Understanding the multifaced roles of α-synuclein in neurodegeneration not only aids in acquiring more knowledge about the pathophysiology of these diseases but also highlights potential biomarkers and therapeutic targets for intervention in alpha-synucleinopathies. In this review, we provide a summary of the mechanisms by which α-synuclein contributes to neurodegenerative processes, focusing on its misfolding, oligomerization, and the formation of insoluble fibrils that form characteristic Lewy bodies. Furthermore, we compare the potential value of α-synuclein species in diagnosing and differentiating selected neurodegenerative diseases.

Asunto(s)

Enfermedades Neurodegenerativas , alfa-Sinucleína , Humanos , alfa-Sinucleína/metabolismo , Enfermedades Neurodegenerativas/metabolismo , Enfermedades Neurodegenerativas/patología , Animales , Pliegue de Proteína , Enfermedad de Parkinson/metabolismo , Enfermedad de Parkinson/patología , Estrés Oxidativo , Atrofia de Múltiples Sistemas/metabolismo , Atrofia de Múltiples Sistemas/patología , Biomarcadores/metabolismo , Agregación Patológica de Proteínas/metabolismo

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Parkinson's disease (PD) and dementia with Lewy bodies (DLB) share underlying neuropathology. Despite overlapping biology, therapeutic development has been approached separately for these clinical syndromes and there remains no treatment to slow, stop or prevent progression of clinical symptoms and development disability for people living with PD or DLB. Recent advances in biomarker tools, however, have paved new paths for biologic definition and staging of PD and DLB under a shared research framework. Patient-centered research funding organizations see the opportunity for a novel biological staging system for PD and DLB to accelerate and increase success of therapeutic development for the patient communities they serve. Amid growing momentum in the field to develop biological definitions for these neurodegenerative diseases, 7 international nonprofit organizations focused on PD and DLB came together to drive multistakeholder discussion and input on a biological staging system for research. The impact of these convenings to date can be seen in changes incorporated into a proposed biological staging system and growing alignment within the field to rapidly apply new scientific knowledge and biomarker tools to inform clinical trial design. In working together, likeminded nonprofit partners who were initially catalyzed by the significant potential for a biological staging system also realized the power of a shared voice in calling the field to action and have since worked together to establish a coalition to advance precompetitive progress and reduce hurdles to developing better treatments for PD, DLB and biologically related disorders.

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Disease-focused nonprofit organizations serve to speed new treatments for patients through research funding and advocacy. In the Parkinson's disease (PD) and dementia with Lewy bodies (DLB) fields, several international nonprofit organizations came together to facilitate multistakeholder input on a new biological staging system for research. Stakeholders gathered included researchers, clinicians, drug developers, regulatory agencies, additional nonprofits, and people affected by PD and DLB. This example, fueled by a shared perspective that new drug development tools will improve clinical trials and get better treatments to patients sooner, serves as a model for continued collaborations across the PD and DLB fields. A new, international coalition of nonprofit organizations has emerged to support advancement of treatments to slow, stop, and one day prevent PD, DLB and related disorders, in part, by facilitating future multistakeholder collaborations.

Asunto(s)

Enfermedad por Cuerpos de Lewy , Enfermedad de Parkinson , Humanos , Enfermedad de Parkinson/terapia , Enfermedad por Cuerpos de Lewy/terapia , Biomarcadores , Organizaciones sin Fines de Lucro

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This study investigates the presence of antinuclear antibodies (ANA) in three primary synucleinopathies - Parkinson's disease (PD), multiple system atrophy (MSA), and dementia with Lewy bodies (DLB), compared to healthy controls. Autoinflammatory disorders typically involve the immune system mistakenly attacking the body's own cells and start producing ANA. There is an increasing body of evidence that immune-mediated inflammation is a pathological feature linked to synucleinopathies. To investigate whether this could be autoimmune mediated we analyzed for ANA in the plasma of 25 MSA, 25 PD, and 17 DLB patients, along with 25 healthy controls, using the ANA HEp-2 indirect immunofluorescence antibody assay (ANA HEp-2 IFA). Contrary to initial expectations, results showed ANA HEp-2 positivity in 12% of PD, 8% of MSA patients, 18% of DLB patients, and 17% of healthy controls, indicating no increased prevalence of ANA in synucleinopathies compared to age-matched healthy individuals. Various ANA HEp-2 patterns were identified, but no specific pattern was associated with individual synucleinopathies. We conclude hereby that synucleinopathies are not associated with detectable presence of ANA in plasma.

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Synucleinopathies are disorders characterized by the aggregation and deposition of pathological α-synuclein conformers. The underlying neurodegenerative processes begin years or decades before the onset of cardinal motor symptoms. This prodromal phase may manifest with various signs or symptoms. However, there are no current standardized laboratory tests to ascertain the progression and conversion of prodromal conditions such as mild cognitive impairment, isolated REM sleep behavior disorder or pure autonomic failure. The aim of this systematic review was to evaluate the diagnostic possibilities using human biofluids as source material to detect pathological α-synuclein in the prodromal phase of synucleinopathies. Our review identified eight eligible studies, that investigated pathological α-synuclein conformers using cerebrospinal fluid from patients with prodromal signs of synulceinopathies to differentiate this patient group from non-synucleinopathies, while only one study investigated this aspect using blood as medium. While previous studies clearly demonstrated a high diagnostic performance of α-synuclein seed amplification assays for differentiating synucleinopathies with Lewy bodies from healthy controls, only few analyses were performed focussing on individuals with prodromal disease. Nevertheless, results for the early detection of α-synuclein seeds using α-synuclein seed amplification assays were promising and may be of particular relevance for future clinical trials and clinical practice.

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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.

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Orexinas , Trastornos del Sueño-Vigilia , Sinucleinopatías , Animales , Humanos , Enfermedad por Cuerpos de Lewy/sangre , Enfermedad por Cuerpos de Lewy/complicaciones , Enfermedad por Cuerpos de Lewy/metabolismo , Atrofia de Múltiples Sistemas/sangre , Atrofia de Múltiples Sistemas/complicaciones , Atrofia de Múltiples Sistemas/metabolismo , Orexinas/sangre , Orexinas/metabolismo , Enfermedad de Parkinson/metabolismo , Enfermedad de Parkinson/complicaciones , Trastornos del Sueño-Vigilia/sangre , Trastornos del Sueño-Vigilia/etiología , Trastornos del Sueño-Vigilia/metabolismo , Sinucleinopatías/sangre , Sinucleinopatías/complicaciones , Sinucleinopatías/metabolismo

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 Pre-formed fibrils (PFFs) made from recombinant α-synuclein are broadly used throughout the field in cellular and animal models of Parkinson's disease. However, their ability to successfully recapitulate disease biology is a controversial topic. In this article, two researchers debate this issue with Amanda Woerman taking the view that PFFs are a model of synucleinopathy but not Parkinson's disease, while Kelvin Luk defends their use as an important tool in the field.

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Parkinson's disease patients develop accumulations of misfolded proteins in the brain called Lewy bodies. An important protein found in Lewy bodies is α-synuclein, which aggregates into large fibrils that are thought to have toxic effects on neurons. To study the effect of α-synuclein fibrils, many scientists use pre-formed fibrils (PFFs), which are α-synuclein fibrils made in the lab under a variety of conditions. In this article, two researchers will debate the use of PFFs as a model of Parkinson's disease. Amanda Woerman discusses the data suggesting why PFFs are an inadequate tool for understanding Parkinson's disease. Kelvin Luk discusses the data supporting the use of PFFs as a Parkinson's disease model.

Asunto(s)

Enfermedad de Parkinson , alfa-Sinucleína , Enfermedad de Parkinson/patología , alfa-Sinucleína/metabolismo , Humanos , Animales

RESUMEN

Key Clinical Message: This case report highlights the challenges of diagnosing MSA-C in resource-limited settings. MRI findings like the "hot cross bun" sign can be supportive, but the unavailability of advanced tools like seed amplification assay may delay diagnosis. Early diagnosis is crucial for proper symptom management. Abstract: Multiple system atrophy is a rare neurodegenerative disorder affecting the pyramidal, autonomic, nigrostriatal, and cerebellar tracts. Multisystem atrophy should be considered in adults with progressive motor or autonomic dysfunctions. Clinical manifestations vary depending on the system, including bradykinesia, tremor, rigidity, cerebellar ataxia, and autonomic failure. Depending on the initial predominant manifestation, multisystem atrophy is classified as Parkinsonian (MSA-P) and cerebellar (MSA-C). Our patient presented with progressive loss of balance, rigidity, slurred speech, choking episodes, and loss of morning tumescence for 4 years, suggesting autonomic and cerebellar involvement. He was diagnosed with MSA after 4 years of initial presentation with combinations of magnetic resonant imaging findings and clinical manifestations. Diagnosing multiple system atrophy in such resource-limited areas is challenging. The unavailability of seed application tests and biomarkers significantly affected the delayed diagnosis.

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There is increasing evidence for blood-brain barrier (BBB) alterations in Parkinson's disease (PD), the second most common neurodegenerative disorder with rapidly rising prevalence. Altered tight junction and transporter protein levels, accumulation of α-synuclein and increase in inflammatory processes lead to extravasation of blood molecules and vessel degeneration. This could result in a self-perpetuating pathophysiology of inflammation and BBB alteration, which contribute to neurodegeneration. Toxin exposure or α-synuclein over-expression in animal models has been shown to initiate similar pathologies, providing a platform to study underlying mechanisms and therapeutic interventions. Here we provide a comprehensive review of the current knowledge on BBB alterations in PD patients and how rodent models that replicate some of these changes can be used to study disease mechanisms. Specific challenges in assessing the BBB in patients and in healthy controls are discussed. Finally, a potential role of BBB alterations in disease pathogenesis and possible implications for therapy are explored. The interference of BBB alterations with current and novel therapeutic strategies requires more attention. Brain region-specific BBB alterations could also open up novel opportunities to target specifically vulnerable neuronal subpopulations.

Asunto(s)

Barrera Hematoencefálica , Enfermedad de Parkinson , Barrera Hematoencefálica/metabolismo , Barrera Hematoencefálica/patología , Humanos , Enfermedad de Parkinson/metabolismo , Enfermedad de Parkinson/terapia , Enfermedad de Parkinson/patología , Animales

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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.

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Encéfalo , Modelos Animales de Enfermedad , Ratones Transgénicos , alfa-Sinucleína , alfa-Sinucleína/metabolismo , alfa-Sinucleína/inmunología , Animales , Humanos , Ratones , Encéfalo/patología , Encéfalo/metabolismo , Sinucleinopatías/patología , Sinucleinopatías/metabolismo , Sinucleinopatías/inmunología , Anticuerpos Monoclonales , Atrofia de Múltiples Sistemas/patología , Atrofia de Múltiples Sistemas/inmunología , Atrofia de Múltiples Sistemas/metabolismo , Priones/inmunología , Priones/metabolismo , Femenino

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Background: Gait disturbance is a vital characteristic of motor manifestation in α- synucleinopathies, especially Parkinson's disease. Subtle gait alterations are present in isolated rapid eye movement sleep behavior disorder (iRBD) patients before phenoconversion; it is yet unclear, if gait analysis may predict phenoconversion. Objective: To investigate subtle gait alterations and explore whether gait analysis using wearable sensors is associated with phenoconversion of iRBD to α-synucleinopathies. Methods: Thirty-one polysomnography-confirmed iRBD patients and 33 healthy controls (HCs) were enrolled at baseline. All participants walked for a minute while wearing 6 inertial sensors on bilateral wrists, ankles, and the trunk (sternal and lumbar region). Three conditions were tested: (i) normal walking, (ii) fast walking, and (iii) dual-task walking. Results: Decreased arm range of motion and increased gait variation (stride length, stride time and stride velocity) discriminate converters from HCs at baseline. After an average of 5.40 years of follow-up, 10 patients converted to neurodegenerative diseases (converters). Cox regression analysis showed higher value of stride length asymmetry under normal walking condition to be associated with an early conversion of iRBD to α- synucleinopathies (adjusted HR 4.468, 95% CI 1.088- 18.349, p = 0.038). Conclusions: Stride length asymmetry is associated with progression to α- synucleinopathies in patients with iRBD. Gait analysis with wearable sensors may be useful for screening, monitoring, and risk stratification for disease-modifying therapy trials in patients with iRBD.

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Análisis de la Marcha , Polisomnografía , Trastorno de la Conducta del Sueño REM , Dispositivos Electrónicos Vestibles , Humanos , Trastorno de la Conducta del Sueño REM/fisiopatología , Trastorno de la Conducta del Sueño REM/diagnóstico , Masculino , Femenino , Anciano , Persona de Mediana Edad , Análisis de la Marcha/instrumentación , Sinucleinopatías/fisiopatología , Sinucleinopatías/diagnóstico , Progresión de la Enfermedad , Enfermedad de Parkinson/fisiopatología , Enfermedad de Parkinson/complicaciones , Enfermedad de Parkinson/diagnóstico , Trastornos Neurológicos de la Marcha/fisiopatología , Trastornos Neurológicos de la Marcha/etiología , Trastornos Neurológicos de la Marcha/diagnóstico

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BACKGROUND: Heterozygous mutations in GBA1 gene are known as most common genetic risk factor for Parkinson's disease (PD). However, role of GBA1 mutations in non-α-synuclein disorders is unclear. CASES: Case index, 76 year-old woman referred to our movement disorders outpatient clinic for 2-year history of gait impairment, falls and motor slowness, with partial response to levodopa. Clinical and instrumental examinations were consistent with Progressive Supranuclear Palsy-Corticobasal Syndrome (PSP-CBS). Case 2 is older sister reporting depressive symptoms; however, she had dementia (MMSE 18/30), gait apraxia and vertical supranuclear gaze palsy (VSNGP). Case 3 is her deceased older sister who had been diagnosed with Corticobasal Syndrome (CBS). Case 4, older brother had been diagnosed with Parkinson's disease-dementia (PDD) with good response to levodopa. Two affected living siblings harboring same genetic variant. CONCLUSIONS: To our knowledge, this is the first family showing such intrafamilial variability ranging from CBS to PDD to dementia.

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Glucosilceramidasa , Enfermedades Neurodegenerativas , Humanos , Glucosilceramidasa/genética , Femenino , Anciano , Masculino , Enfermedades Neurodegenerativas/genética , Enfermedades Neurodegenerativas/diagnóstico , Italia , Enfermedad de Parkinson/genética , Enfermedad de Parkinson/complicaciones , Mutación , Parálisis Supranuclear Progresiva/genética

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The aggregation of alpha-synuclein (aSyn) represents a neuropathological hallmark observed in a group of neurodegenerative disorders collectively known as synucleinopathies. Despite their shared characteristics, these disorders manifest diverse clinical and pathological phenotypes. The mechanism underlying this heterogeneity is thought to be due to the diversity in the aSyn strains present across the diseases. In this perspective, we will explore recent findings on aSyn strains and discuss recent discoveries about Lewy bodies' composition. We further discuss the current hypothesis for aSyn spreading and emphasize the emerging biomarker field demonstrating promising results. A comprehension of these mechanisms holds substantial promise for future clinical applications. This understanding can pave the way for the development of personalized medicine strategies, specifically targeting the unique underlying causes of each synucleinopathy. Such advancements can revolutionize therapeutic approaches and significantly contribute to more effective interventions in the intricate landscape of neurodegenerative disorders.

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Parkinson's disease (PD) is a neurodegenerative disorder characterized by the progressive loss of dopaminergic neurons in the substantia nigra pars compacta region of the midbrain and the formation of intracellular protein aggregates known as Lewy bodies, of which a major component is the protein α-synuclein. Several studies have suggested that mitochondria play a central role in the pathogenesis of PD, encompassing both familial and sporadic forms of the disease. Mitochondrial dysfunction is attributed to bioenergetic impairment, increased oxidative stress, damage to mitochondrial DNA, and alteration in mitochondrial morphology. These alterations may contribute to improper functioning of the central nervous system and ultimately lead to neurodegeneration. The perturbation of mitochondrial function makes it a potential target, worthy of exploration for neuroprotective therapies and to improve mitochondrial health in PD. Thus, in the current review, we provide an update on mitochondria-based therapeutic approaches toward α-synucleinopathies in PD.

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Mitocondrias , Enfermedad de Parkinson , Sinucleinopatías , Humanos , Enfermedad de Parkinson/terapia , Enfermedad de Parkinson/metabolismo , Sinucleinopatías/metabolismo , Sinucleinopatías/terapia , Mitocondrias/metabolismo , Animales , alfa-Sinucleína/metabolismo

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Neurodegenerative diseases are commonly classified as proteinopathies that are defined by the aggregation of a specific protein. Parkinson's disease (PD) and dementia with Lewy bodies (DLB) are classified as synucleinopathies since α-synuclein (α-syn)-containing inclusions histopathologically define these diseases. Unbiased biochemical analysis of PD and DLB patient material unexpectedly revealed novel pathological inclusions in the nucleus comprising adenosine-to-inosine (A-to-I)-edited mRNAs and NONO and SFPQ proteins. These inclusions showed no colocalization with Lewy bodies and accumulated at levels comparable to α-syn. NONO and SFPQ aggregates reduced the expression of the editing inhibitor ADAR3, increasing A-to-I editing mainly within human-specific, Alu-repeat regions of axon, synaptic, and mitochondrial transcripts. Inosine-containing transcripts aberrantly accumulated in the nucleus, bound tighter to recombinant purified SFPQ in vitro, and potentiated SFPQ aggregation in human dopamine neurons, resulting in a self-propagating pathological state. Our data offer new insight into the inclusion composition and pathophysiology of PD and DLB.

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Enfermedad por Cuerpos de Lewy , Factor de Empalme Asociado a PTB , Enfermedad de Parkinson , Edición de ARN , Humanos , Enfermedad por Cuerpos de Lewy/metabolismo , Enfermedad por Cuerpos de Lewy/patología , Enfermedad por Cuerpos de Lewy/genética , Enfermedad de Parkinson/metabolismo , Enfermedad de Parkinson/genética , Enfermedad de Parkinson/patología , Factor de Empalme Asociado a PTB/metabolismo , Factor de Empalme Asociado a PTB/genética , Proteínas de Unión al ARN/metabolismo , Proteínas de Unión al ARN/genética , Inosina/metabolismo , Adenosina/metabolismo , Núcleo Celular/metabolismo , Masculino , Anciano , Adenosina Desaminasa/genética , Adenosina Desaminasa/metabolismo , Femenino , ARN Mensajero/metabolismo , alfa-Sinucleína/metabolismo , alfa-Sinucleína/genética , Neuronas Dopaminérgicas/metabolismo , Neuronas Dopaminérgicas/patología , Anciano de 80 o más Años

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OBJECTIVE: Evidence of abnormal α-synuclein (α-Syn) deposition in the brain is required for definitive diagnosis of synucleinopathies, which remains challenging. The seed amplification assay (SAA) is an innovative technique that can detect the seeding activity of misfolded α-Syn, enabling the amplification and detection of minute quantities of pathogenic α-Syn aggregates. This study aimed to evaluate oral mucosa α-Syn SAA as possible diagnostic and prodromal biomarkers for synucleinopathies. METHODS: A total of 107 Parkinson's disease (PD) patients, 99 multiple system atrophy (MSA) patients, 33 patients with isolated rapid eye movement sleep behavior disorder (iRBD) and 103 healthy controls (HC) were included. The SAA was applied to detect the seeding activity of α-Syn from oral mucosa. A combination of morphological, biochemical, and biophysical methods was also used to analyze the fibrils generated from the oral mucosa α-Syn SAA. RESULTS: Structured illumination microscopy images revealed the increased α-Syn species in oral mucosa of PD, MSA, and iRBD patients than in HCs. Oral mucosa α-Syn SAA distinguished patients with PD from HC with 67.3% sensitivity and 90.3% specificity. Oral mucosa was α-Syn SAA positive in 53.5% MSA patients and 63.6% iRBD patients. Furthermore, the α-Syn fibrils generated from MSA demonstrated greater resistance to proteinase K digestion and exhibited stronger cytotoxicity compared to those from PD patients. CONCLUSION: Oral mucosa α-Syn seeding activity may serve as novel non-invasive diagnostic and prodromal biomarkers for synucleinopathies. The α-Syn aggregates amplified from the oral mucosa of PD and MSA exhibited distinct biochemical and biophysical properties. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

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Mucosa Bucal , Atrofia de Múltiples Sistemas , Enfermedad de Parkinson , Trastorno de la Conducta del Sueño REM , Sinucleinopatías , alfa-Sinucleína , Humanos , Trastorno de la Conducta del Sueño REM/metabolismo , Trastorno de la Conducta del Sueño REM/diagnóstico , alfa-Sinucleína/metabolismo , Femenino , Masculino , Enfermedad de Parkinson/metabolismo , Enfermedad de Parkinson/diagnóstico , Persona de Mediana Edad , Anciano , Sinucleinopatías/metabolismo , Mucosa Bucal/metabolismo , Mucosa Bucal/patología , Atrofia de Múltiples Sistemas/metabolismo , Atrofia de Múltiples Sistemas/diagnóstico , Atrofia de Múltiples Sistemas/genética , Atrofia de Múltiples Sistemas/patología , Biomarcadores/metabolismo

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Parkinson's Disease (PD) patients experience sleeping disorders in addition to the disease-defining symptomology of movement dysfunctions. The prevalence of PD is sex-based and presence of sleeping disorders in PD also shows sex bias with a stronger phenotype in males. In addition to loss of dopamine-containing neurons in the striatum, arousal-related, orexin-containing neurons in the lateral hypothalamus (LH) are lost in PD, which could contribute to state-related disorders. As orexin has been shown to be involved in sleeping disorders and to have neuroprotective effects, we asked whether orexin could protect sleep-related LH neurons from damage putatively from the protein α-synuclein (α-syn), which is found at high levels in the PD brain and that we have shown is associated with putatively excitotoxic rises in intracellular calcium in brainstem sleep-controlling nuclei, especially in males. Accordingly, we monitored intracellular calcium transients induced by α-syn and whether concurrent exposure to orexin affected those transients in LH cells of the mouse brain slice using calcium imaging. Further, we used an assay of cell death to determine whether LH cell viability was influenced when α-syn and orexin were co-applied when compared to exposure to α-syn alone. We found that excitatory calcium events induced by α-syn were reduced in amplitude and frequency when orexin was co-applied, and when data were evaluated by sex, this effect was found to be greater in females. In addition, α-syn exposure was associated with cell death that was higher in males, and interestingly, reduced cell death was noted when orexin was present, which did not show a sex bias. We interpret our findings to indicate that orexin is protective to α-syn-mediated damage to hypothalamic neurons, and the actions of orexin on α-syn-induced cellular effects differ between sexes, which could underlie sex-based differences in sleeping disorders in PD.

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Calcio , Muerte Celular , Área Hipotalámica Lateral , Neuronas , Orexinas , alfa-Sinucleína , Animales , Orexinas/metabolismo , Orexinas/farmacología , Masculino , Ratones , Neuronas/metabolismo , Neuronas/efectos de los fármacos , Femenino , Área Hipotalámica Lateral/metabolismo , Área Hipotalámica Lateral/efectos de los fármacos , alfa-Sinucleína/metabolismo , Muerte Celular/efectos de los fármacos , Calcio/metabolismo , Ratones Endogámicos C57BL , Caracteres Sexuales

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INTRODUCTION: Identifying biomarkers reflecting cellular dysfunctions in early Parkinson's disease patients (ePD) is needed to develop targeted therapeutic strategies. We aimed to determine if cellular energetic dysfunction related to increased brain sodium concentration would be co-located to microstructural alterations and iron deposition in ePD. METHODS: We prospectively included 12 ePD (mean disease duration 20.0 ± 10.2 months) and 13 healthy controls (HC), scanned with a 7 T 1H and 23Na MRI. Complementary voxel-based and region-based assessments were performed, the latter utilizing a high-resolution multimodal template we created (combining quantitative T1 maps (qT1), transverse relaxation rate (R2*), quantitative magnetic susceptibility mapping (QSM) images) from 200 subjects. This template allowed a precise multiparametric assessment of sodium concentration, QSM, R2*, qT1, mean diffusivity, and fractional anisotropy values. A two-sided p-value<0.05 was considered statistically significant after the Bonferroni correction. RESULTS: Relative to HC, ePD showed significantly higher sodium concentration in left Substantia nigra (SN) pars reticulata (46.13 mM ± 3.52 vs 38.60 mM ± 6.10, p = 0.038), a subpart of the SN pars compacta (SNc) and ventral tegmental area, Putamen, Globus Pallidum external, accumbens nucleus and claustrum. Significantly increased QSM and R2* values, and decreased T1 values, were limited to the Nigrosomes 1 (Nig) and right SNc (all p < 0.05). QSM values in the Nig were significantly correlated to UPDRS-III scores (r = 0.91,p < 0.001). CONCLUSION: In ePD, brain sodium accumulation was broad and dissociated from iron accumulation. As with iron accumulation, a sodium-related pathophysiological approach could lead to identifying potential new therapeutic agents and deserves further investigation.

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Sobrecarga de Hierro , Imagen por Resonancia Magnética , Enfermedad de Parkinson , Humanos , Enfermedad de Parkinson/metabolismo , Enfermedad de Parkinson/diagnóstico por imagen , Enfermedad de Parkinson/fisiopatología , Masculino , Femenino , Persona de Mediana Edad , Anciano , Sobrecarga de Hierro/metabolismo , Sodio/metabolismo , Sustancia Negra/diagnóstico por imagen , Sustancia Negra/metabolismo , Metabolismo Energético/fisiología , Estudios Prospectivos

RESUMEN

Oligomeric alpha-synuclein (α-syn) in saliva and phosphorylated α-syn deposits in the skin have emerged as promising diagnostic biomarkers for Parkinson's disease (PD). This study aimed to assess and compare the diagnostic value of these biomarkers in discriminating between 38 PD patients and 24 healthy subjects (HSs) using easily accessible biological samples. Additionally, the study sought to determine the diagnostic potential of combining these biomarkers and to explore their correlations with clinical features. Salivary oligomeric α-syn levels were quantified using competitive ELISA, while skin biopsies were analyzed through immunofluorescence to detect phosphorylated α-syn at Ser129 (p-S129). Both biomarkers individually were accurate in discriminating PD patients from HSs, with a modest agreement between them. The combined positivity of salivary α-syn oligomers and skin p-S129 aggregates differentiated PD patients from HSs with an excellent discriminative ability with an AUC of 0.9095. The modest agreement observed between salivary and skin biomarkers individually suggests that they may reflect different aspects of PD pathology, thus providing complementary information when combined. This study's results highlight the potential of utilizing a multimodal biomarker approach to enhance diagnostic accuracy in PD.

Asunto(s)

Biomarcadores , Enfermedad de Parkinson , Saliva , Piel , alfa-Sinucleína , Humanos , Enfermedad de Parkinson/diagnóstico , Enfermedad de Parkinson/metabolismo , Saliva/metabolismo , Biomarcadores/metabolismo , Masculino , Femenino , alfa-Sinucleína/metabolismo , alfa-Sinucleína/análisis , Persona de Mediana Edad , Anciano , Piel/metabolismo , Piel/patología , Fosforilación , Estudios de Casos y Controles

RESUMEN

BACKGROUND: α-Synuclein (αS) aggregation is the main neurological hallmark of a group of neurodegenerative disorders, collectively referred to as synucleinopathies, of which Parkinson's disease (PD) is the most prevalent. αS oligomers are elevated in the cerebrospinal fluid (CSF) of PD patients, standing as a biomarker for disease diagnosis. However, methods for early PD detection are still lacking. We have recently identified the amphipathic 22-residue peptide PSMα3 as a high-affinity binder of αS toxic oligomers. PSMα3 displayed excellent selectivity and reproducibility, binding to αS toxic oligomers with affinities in the low nanomolar range and without detectable cross-reactivity with functional monomeric αS. RESULTS: In this work, we leveraged these PSMα3 unique properties to design a plasmonic-based biosensor for the direct detection of toxic oligomers under label-free conditions. SIGNIFICANCE AND NOVELTY: We describe the integration of the peptide in a lab-on-a-chip plasmonic platform suitable for point-of-care measurements of αS toxic oligomers in CSF samples in real-time and at an affordable cost, providing an innovative biosensor for PD early diagnosis in the clinic.

Asunto(s)

Enfermedades Neurodegenerativas , Enfermedad de Parkinson , Humanos , alfa-Sinucleína , Reproducibilidad de los Resultados , Enfermedad de Parkinson/diagnóstico , Péptidos