Plasma Α-synuclein Research Articles

Measurement of α-synuclein as protein cargo in plasma extracellular vesicles

Extracellular vesicles (EVs) are released by all cells and hold great promise as a class of biomarkers. This promise has led to increased interest in measuring EV proteins from both total EVs as well as brain-derived EVs in plasma. However, measuring cargo proteins in EVs has been challenging because EVs are present at low levels, and EV isolation methods are imperfect at separating EVs from free proteins. Thus, knowing whether a protein measured after EV isolation is truly inside EVs is difficult. In this study, we developed methods to measure whether a protein is inside EVs and quantify the ratio of a protein in EVs relative to total plasma. To achieve this, we combined a high-yield size-exclusion chromatography protocol with an optimized protease protection assay and Single Molecule Array (Simoa) digital enzyme-linked immunoassays (ELISAs) for ultrasensitive measurement of proteins inside EVs. We applied these methods to analyze α-synuclein and confirmed that a small fraction of the total plasma α-synuclein is inside EVs. Additionally, we developed a highly sensitive Simoa assay for phosphorylated α-synuclein (phosphorylated at the Ser129 residue). We found enrichment in the phosphorylated α-synuclein to total α-synuclein ratio inside EVs relative to outside EVs. Finally, we applied the methods we developed to measure total and phosphorylated α-synuclein inside EVs from Parkinson's disease and Lewy body dementia patient samples. This work provides a framework for determining the levels of proteins in EVs and represents an important step in the development of EV diagnostics for diseases of the brain, as well as other organs.

Value of plasma alpha- and beta-synuclein levels in the diagnosis, severity, and functional outcome of acute ischemic stroke

Abstract OBJECTIVE: We aimed to determine the role of plasma alpha- and beta-synuclein levels and other routine inflammatory parameters in the diagnosis, outcome, and mortality of acute ischemic stroke (AIS). METHODS: In our study, serum alpha- and beta-synuclein levels and clinical data were prospectively evaluated in 93 subjects (43 controls and 50 AIS patients) admitted to the emergency department. The outcome status and prognostic classification were performed according to the modified Rankin Scale (mRS) scores on the 30th day from hospital admission. RESULTS: The mean age of the subjects was 70.6 ± 11 years. Thirty-eight percentage were female. Plasma α-synuclein levels in the AIS group (33.6 ± 8.5 ng/mL) were significantly higher than those in the control group (4.22 ± 2.1 ng/mL) (P < 0.001). Plasma β-synuclein levels in the AIS group (13.07 ± 2.7 ng/mL) were significantly higher than those in the control group (2.17 ± 1.4 ng/mL) (P < 0.001). There was no significant difference in alpha- and beta-synuclein levels between the subgroups formed according to the 30th-day results of the patients using the mRS scores (P = 0.813 and 0.812, respectively). CONCLUSION: The serum alpha- and beta-synuclein concentrations of patients with AIS at admission were significantly higher than the healthy control group. At admission, serum alpha- and beta-synuclein levels do not have definitive clinically predictive value in predicting stroke progression and outcome in patients with AIS.

Safety, Tolerability, and Pharmacokinetics of Single Doses of Exidavnemab (BAN0805), an Anti-α-Synuclein Antibody, in Healthy Western, Caucasian, Japanese, and Han Chinese Adults.

Exidavnemab is a monoclonal antibody (mAb) with a high affinity and selectivity for pathological aggregated forms of α-synuclein and a low affinity for physiological monomers, which is in clinical development as a disease-modifying treatment for patients with synucleinopathies such as Parkinson's disease. Safety, tolerability, pharmacokinetics, immunogenicity, and exploratory biomarkers were assessed in two separate Phase 1 single ascending dose studies, including single intravenous (IV) (100 to 6000 mg) or subcutaneous (SC) (300 mg) administration of exidavnemab in healthy volunteers (HVs). Across the two studies, a total of 98 Western, Caucasian, Japanese, and Han Chinese HVs were enrolled, of which 95 completed the study. Exidavnemab was generally well tolerated. There were no serious adverse events or safety issues identified in laboratory analyses. Headache, asymptomatic COVID-19, back pain, and post lumbar puncture syndrome were the most frequently reported treatment-emergent adverse events. Following IV infusion, the pharmacokinetics of exidavnemab was approximately dose linear in the range 100-6000mg. The terminal half-life was approximately 30 days, and the exposure was comparable across Western, Caucasian, Japanese, and Han Chinese volunteers. The absolute SC bioavailability was ∼71%. Cerebrospinal fluid exposure relative to serum after single dose was within the range expected for mAbs (approximately 0.2%). The anti-drug antibody rates were low and there was no effect of immunogenicity on the pharmacokinetics or safety. Dose-dependent reduction of free α-synuclein in plasma was observed. In summary, exidavnemab was found to have an excellent pharmacokinetic profile and was well tolerated in HVs, supporting the continued clinical development.

Pain-Free Alpha-Synuclein Detection by Low-Cost Hierarchical Nanowire Based Electrode.

Analytical methods for the early detection of the neurodegenerative biomarker for Parkinson's disease (PD), α-synuclein, are time-consuming and invasive, and require skilled personnel and sophisticated and expensive equipment. Thus, a pain-free, prompt and simple α-synuclein biosensor for detection in plasma is highly demanded. In this paper, an α-synuclein electrochemical biosensor based on hierarchical polyglutamic acid/ZnO nanowires decorated by gold nanoparticles, assembled as nanostars (NSs), for the determination of α-synuclein in human plasma is proposed. ZnO NSs were prepared by chemical bath deposition (CBD) and decorated with electrodeposited Au nanoparticles (Au NPs). Then, electro-polymerized glutamic acid was grown and functionalized with anti-α-synuclein. A synergistic enhancement of electrode sensitivity was observed when Au NPs were embedded into ZnO NSs. The analytical performance of the biosensor was evaluated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), using the Fe(II)(CN)64-/Fe(III)(CN)63- probe. The charge transfer resistance after α-synuclein recognition was found to be linear, with a concentration in the range of 0.5 pg·mL-1 to 10 pg·mL-1, a limit of detection of 0.08 pg·mL-1, and good reproducibility (5% variation) and stability (90%). The biosensor was also shown to reliably discriminate between healthy plasma and PD plasma. These results suggest that the proposed biosensor provides a rapid, quantitative and high-sensitivity result of the α-synuclein content in plasma, and represents a feasible tool capable of accelerating the early and non-invasive identification of Parkinson's disease.

METTL14 is decreased and regulates m6 A modification of α-synuclein in Parkinson's disease.

N6-methyladenosine (m6A), an emerging modification of messenger RNA, has been implicated in many biological processes. However, its role in Parkinson's disease (PD) remains largely unknown. Here, we investigated the role of m6A modification and its underlying mechanism in PD. First, 86 individuals with PD and 86 healthy controls were recruited from a pilot multicenter cohort. Levels of m6A and its modulators in peripheral blood mononuclear cells of patients with PD and controls were measured using an m6A RNA methylation quantification kit and quantitative real-time PCR. The underlying mechanism of m6A modification in PD was investigated in vitro through RNA immunoprecipitation assay, RNA stability assay, gene silencing or overexpression, western blot, and confocal immunoassay. The results show that mRNA levels of m6A, METTL3, METTL14, and YTHDF2 in patients with PD were significantly lower than in healthy controls, and METTL14 was the main factor involved in abnormal m6A modification. Area under the curve (AUC) analysis suggests METTL14 may provide excellent diagnostic capability for PD, especially when combined with plasma α-synuclein (α-syn). Spearman correlation analysis identified that METTL14 was moderately negatively correlated with plasma α-syn and the motor function of PD. Mechanistic experiments demonstrated that Mettl14 targets and regulates the expression of the α-syn gene using its methylation function. Overexpression of Mettl14 dramatically increased m6 A modification of α-syn mRNA and weakened its stability. Further results suggest that α-syn mRNA was modified by Mettl14 binding of an m6 A motif in the coding region of α-syn mRNA, while the reading protein Ythdf2 was involved in recognizing m6 A-modified α-syn mRNA. Taken together, our results reveal the potential of METTL14 as a novel diagnostic biomarker for PD and identify modification of pathogenic α-syn protein by METTL14 via an m6 A-YTHDF2-dependent mechanism.

Assessment of Plasma Biomarkers by ImmunoMagnetic Reduction in Parkinson’s Disease Dementia and Dementia with Lewy Bodies (P10-6.008)

<h3>Objective:</h3> To use ImmunoMagnetic Reduction (IMR) assay to assess the diagnostic utility of plasma Aβ42, total Tau (t-Tau), phosphorylated Tau-181 (p-Tau-181) and α-synuclein in identifying and differentiating cases of Parkinson’s Disease Dementia (PDD) and Dementia with Lewy Bodies (DLB). <h3>Background:</h3> PDD and DLB represent pathological subtypes along a continuum of synucleinopathies. Clinical differentiation is ultimately based on arbitrary and subjectively-reported timing of cognitive and motor symptoms. Ancillary tests are invasive, costly, and exhibit suboptimal sensitivity and specificity. Developments in plasma biomarker assays have increased detection thresholds and provide the opportunity to reassess whether core PDD/DLB plasma biomarkers would be useful for diagnosis. <h3>Design/Methods:</h3> Plasma samples from 61 total subjects (37 normal controls (NC), 12 with PDD, 12 with DLB) and were sent for IMR assay to quantify α-synuclein, Aβ42, t-Tau, and p-Tau-181. To determine discrimination between NC, PDD, and DLB, receiver operating characteristic (ROC) curve analysis was used to obtain sensitivity, specificity, and area under curve (AUC). <h3>Results:</h3> Plasma p-tau levels were significantly higher in DLB compared to NC and PD (p&lt;0.05). Plasma α-synuclein levels were significantly higher in PDD compared to DLB and NC. Plasma t-Tau and Aβ42 levels did not differ between NC, PDD and DLB subjects. When plasma biomarkers were combined, Aβ42 x t-Tau revealed no differences between DLB, PDD and NC. For the α-synuclein x p-Tau-181 combination, both PDD and DLB were greater than NC. <h3>Conclusions:</h3> Investigations into the discrimination of DLB vs. PDD are rare. In this pilot study, we show that IMR assays of plasma for α-synuclein, p-Tau-181, and Aβ42 x t-tau are useful in differentiating PDD from DLB, as well as NC. Thus, our data suggest clinical utility of these novel biomarker modalities and panels. Differentiating DLB from PDD could be consequential in clinical characterization. Future studies will aim to replicate our findings on larger group sizes. <b>Disclosure:</b> Dr. Malaty has nothing to disclose. Dr. Lue has nothing to disclose. Dr. Shill has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Amneal Pharmaceuticals. Dr. Shill has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Neurocrine Biosciences. Dr. Shill has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Biogen. Dr. Shill has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Abbive. Dr. Decourt has received personal compensation for serving as an employee of Cleveland Clinic. Dr. Decourt has received personal compensation in the range of $0-$499 for serving as a Reviewer with NIH. Dr. Sabbagh has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Eisai. Dr. Sabbagh has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Genetech=Roche. Dr. Sabbagh has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Novo Nordisk. Dr. Sabbagh has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Lilly. Dr. Sabbagh has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Synaptogenix. Dr. Sabbagh has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Signant Health. Dr. Sabbagh has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for T3D. Dr. Sabbagh has received personal compensation in the range of $10,000-$49,999 for serving as an officer or member of the Board of Directors for EIP Pharma. Dr. Sabbagh has received personal compensation in the range of $10,000-$49,999 for serving as an officer or member of the Board of Directors for Quince-Cortexyme. Dr. Sabbagh has stock in Neurotau. Dr. Sabbagh has stock in Seq Biomarque. Dr. Sabbagh has stock in uMethod Health. Dr. Sabbagh has stock in Athira. Dr. Sabbagh has stock in Lighthouse Pharmaceuticals. Dr. Sabbagh has stock in Alzheom. The institution of Dr. Sabbagh has received research support from NIH. The institution of Dr. Sabbagh has received research support from ADDF. Dr. Sabbagh has received publishing royalties from a publication relating to health care.

Mendelian Randomization Analysis Reveals No Causal Relationship Between Plasma α-Synuclein and Parkinson's Disease.

So far, the studies exploring plasma α-synuclein as a biomarker of Parkinson's disease (PD) have provided contradictory results. Here, we first employed the Mendelian randomization (MR) approach to elucidate their potential causal relationship. Five genetic instrumental variables of plasma α-synuclein were acquired from two publicly available datasets. Three independent genome-wide association studies of PD were used as outcome cohorts (PD cohorts 1, 2, and 3). Two-sample MR analyses were conducted using inverse-variance weighted (IVW), MR-Egger, weighted median, simple mode, and leave-one-out methods. Though the IVW approach demonstrated positive plasma α-synuclein effect on the PD risk in three outcome cohorts (OR = 1.134, 1.164, and 1.189, respectively), the P values were all larger than 0.05. The conclusions were robust under complementary sensitivity analyses. Our results did not support the causal relationship between plasma α-synuclein and PD.

A task-specific cognitive domain decline is correlated with plasma and neuroimaging markers in patients with Parkinson's disease.

Cognitive impairment is a disabling non-motor symptom of Parkinson's disease (PD). It remains uncertain whether declines in specific cognitive domains relate to imaging or plasma biomarkers across the disease continuum. We investigated whether neuroimaging and plasma biomarkers correlate with individual task-specific cognitive domain declines evidenced by computerized neuropsychological tests in PD patients. A total of 107 participants, including 87 PD patients (30 with normal cognition [PD-NC], 30 with mild cognitive impairment [PD-MCI], 27 with dementia [PDD]), and 20 healthy controls, were recruited. All received the Cambridge Neuropsychological Test Automatic Battery (CANTAB) test, brain MRI, and assays of plasma biomarkers, including α-synuclein, tau, Aβ42, and Aβ40. PD patients had generally poorer cognitive performance than controls. Patients with PD-MCI and PDD had worse performance in visual, verbal, and working memory and executive function than those with PD-NC. After adjusting for covariates, PDD patients had global cortical thinning, especially in the temporal and parietal lobes, and higher plasma α-synuclein levels and tau:Aβ42 ratios than PD-NC group. Plasma α-synuclein level was associated with frontal lobe-mediated tasks, while the tau:Aβ42 ratio was associated with posterior cortical-mediated tasks. Facial emotion recognition tasks and visual pattern recognition associated with frontotemporal cortical thinning. The accuracy of predicting PDD using age alone (area under the curve [AUC] 0.756) increased by incorporating plasma biomarkers (AUC = 0.851, p = 0.025). Cognitive decline in PD patients has a task-specific correlation with neuroimaging and plasma biomarkers, which may implicate the underlying neuropathological process of PDD.

Synuclein Motor Dysfunction Composite Scale for the Discrimination of Dementia With Lewy Bodies From Alzheimer's Disease.

BackgroundAn abnormal increase of α-synuclein in the brain is the hallmark of dementia with Lewy bodies (DLB). However, the diagnostic power of plasma α-synuclein in DLB is not yet confirmed. Parkinsonism is highly associated with and is one of the core clinical features of DLB. We studied plasma α-synuclein and developed a novel tool that combined plasma α-synuclein level and Motor Dysfunction Questionnaire (MDQ), namely Synuclein Motor Dysfunction Composite Scale (SMDCS), for the clinical discrimination of DLB from Alzheimer’s disease (AD).MethodsThis cross-sectional study analyzed participants’ demographical data, plasma α-synuclein level, MDQ, structured clinical history questionnaire, neuropsychological and motor function tests, and neuroimaging studies. The power of plasma α-synuclein level, MDQ, and SMDCS for discriminating DLB from non-demented controls (NC) or AD were compared.ResultsOverall, 121 participants diagnosed as 58 DLB, 31 AD, and 31 NC were enrolled. Patients with DLB had significantly higher mean plasma α-synuclein level (0.24 ± 0.32 pg/ml) compared to the NC group (0.08 ± 0.05 pg/ml) and the AD group (0.08 ± 0.05 pg/ml). The DLB group demonstrated higher MDQ (2.95 ± 1.60) compared to the NC (0.42 ± 0.98) or AD (0.44 ± 0.99) groups. The sensitivity/specificity of plasma α-synuclein level, MDQ, and SMDCS for differentiating DLB from non-DLB were 0.80/0.64, 0.83/0.89, and 0.88/0.93, respectively.ConclusionBoth plasma α-synuclein and MDQ were significantly higher in patients with DLB compared to the NC or AD groups. The novel SMDCS, significantly improved accuracy for the clinical differentiation of DLB from AD or NC.

Plasma α-synuclein and phosphorylated tau 181 as a diagnostic biomarker panel for de novo Parkinson's disease.

The use of a diagnostic panel comprising multiple biomarkers has the potential to accurately diagnose Parkinson’s disease (PD). However, a panel consisting solely of plasma biomarkers to diagnose PD is not available. This study aimed to examine the diagnostic ability of plasma biomarker panels for de novo PD using novel digital ultrasensitive immunoassay technology. We recruited 45 patients with de novo PD and 20 healthy controls (HCs). The concentrations of plasma α‐synuclein (α‐syn), amyloid β‐42 (Aβ42), Aβ40, phosphorylated tau 181 (p‐tau181), neurofilament light (NFL), and glial fibrillary acidic protein (GFAP) were quantified using the ultrasensitive single molecule array (Simoa) platform. Patients with de novo PD had higher plasma levels of α‐syn and p‐tau181 than HCs, adjusting for age and sex. Plasma levels of α‐syn and p‐tau181 were positively correlated in de novo PD patients. Higher plasma α‐syn levels were significantly associated with worse Unified Parkinson’s Disease Rating Scale (UPDRS) Part III motor scores, modified Hoehn and Yahr (H‐Y) stages, and increased risk of PD with mild cognitive impairment (PD‐MCI). Higher plasma p‐tau181 concentrations were linked to worse H‐Y stages. The diagnostic panel using plasma α‐syn and p‐tau181, combined with age and sex, showed good performance in discriminating de novo PD patients from HCs (area under the curve = 0.806). These findings suggest that plasma α‐syn and p‐tau181 together may be a promising diagnostic biomarker panel for de novo PD patients.

Association of plasma α-synuclein with cardiac 123I-MIBG scintigraphy in early Parkinson’s disease

Cardiac 123I-metaiodobenzylguanidine (MIBG) uptake correlates with the extent of cardiac sympathetic denervation found in disease with Lewy pathology, such as Parkinson’s disease (PD). Protein α-synuclein, the main component of Lewy body, is a candidate biomarker of PD, but its relationship with cardiac MIBG uptake has never been explored. Plasma α-synuclein levels were measured in 37 patients with early PD. Cardiac 123I-MIBG scintigraphy and 18F-FP-CIT brain PET were performed, and striatal dopamine transporter (DAT) uptake was quantified using automated segmentation. The relationships of plasma α-synuclein levels with cardiac MIBG and striatal DAT uptake were investigated. The plasma α-synuclein level correlated with early (R = 0.38, P = 0.033) and delayed (R = 0.49, P = 0.0055) MIBG heart-to-mediastinum (H/M) ratios, and its correlation with delayed H/M ratio remained significant after adjustment with age, disease duration, motor severity, and striatal DAT uptake (P = 0.016). The regional SUVRs of any subregions of caudate and putamen did not correlate with plasma α-synuclein level. In the patients with early PD, the plasma α-synuclein level correlated with cardiac sympathetic denervation, but not with nigrostriatal degeneration. This may suggest that plasma α-synuclein levels more readily reflect the peripheral deposition of Lewy bodies than their central deposition.

Can Plasma α-Synuclein Help Us to Differentiate Parkinson's Disease from Essential Tremor?

Background:Studies have revealed controversial results regarding the diagnostic accuracy of plasma α-synuclein levels in patients with Parkinson’s disease (PD). This study was aimed to analyze the diagnostic accuracy of plasma α-synuclein in PD versus healthy controls and patients with essential tremor (ET).Methods:In this cross-sectional study, we included de novo (n = 19) and advanced PD patients [OFF (n = 33), and On (n = 35) states], patients with ET (n = 19), and controls (n = 35). The total plasma α-synuclein levels were determined using an ELISA sandwich method. We performed adjusted multivariate regression analysis to estimate the association of α-synuclein levels with group conditions [controls, ET, and de novo, OFF and ON-PD]. We studied the diagnostic accuracy of plasma α-synuclein using the area under the curve (AUC).Results:The plasma α-synuclein levels were higher in controls compared to PD and ET (p < 0.0001), discriminating de novo PD from controls (AUC = 0.74, 95% CI 0.60–0.89), with a trend towards in advanced PD (OFF state) from ET (AUC = 0.69, 95% CI 0.53–0.84).Conclusions:This is the first study examining and comparing plasma α-synuclein levels in ET vs. PD and controls. Preliminary findings suggest that plasma α-synuclein levels might help to discriminate de novo and advanced PD from controls and ET.

Linking Stage-Specific Plasma Biomarkers to Gray Matter Atrophy in Parkinson Disease.

The shortcomings of synucleinopathy-based Parkinson disease staging highlight the need for systematic clinicopathologic elucidation and biomarkers. In this study, we investigated associations of proteinopathy and inflammation markers with changes in gray matter volume that accompany Parkinson disease progression. We prospectively enrolled 42 patients with idiopathic Parkinson disease, subdivided into early-/late-stage groups and 27 healthy controls. Parkinson disease severity and participants' functional and cognitive performance were evaluated. Peripheral plasma α-synuclein, β-amyloid42, and tau were quantified with immunomagnetic reduction assays, and nuclear DNA by polymerase chain reaction, and regional gray matter volumes were determined by MR imaging. Statistical tests identified stage-specific biomarkers and gray matter volume patterns in the early-stage Parkinson disease, late-stage Parkinson disease, and control groups. Correlations between gray matter volume atrophy, plasma biomarkers, Parkinson disease severity, and cognitive performance were analyzed. Patients with Parkinson disease had significantly elevated α-synuclein, tau, and β-amyloid42 levels compared with controls; nuclear DNA levels were similar in early-stage Parkinson disease and controls, but higher in late-stage Parkinson disease (all P < .01). We identified 3 stage-specific gray matter volume atrophy patterns: 1) control > early-stage Parkinson disease = late-stage Parkinson disease: right midfrontal, left lingual, and fusiform gyri, left hippocampus, and cerebellum; 2) control > early-stage Parkinson disease > late-stage Parkinson disease: precentral, postcentral, parahippocampal, left superior-temporal, right temporal, right superior-frontal, and left cingulate gyri, occipital lobe, and bilateral parts of the cerebellum; 3) control = early-stage Parkinson disease > late-stage Parkinson disease: left midfrontal, superior-frontal and temporal, amygdala, and posterior cingulate gyri, caudate nucleus, and putamen. We discovered stage-specific correlations among proteinopathy, inflammation makers, topographic gray matter volume patterns, and cognitive performance that accompanied Parkinson disease progression. Identifying associations linking peripheral plasma biomarkers, gray matter volume, and clinical status in Parkinson disease may facilitate earlier diagnosis and improve prognostic accuracy.

Lower Plasma α-Synuclein Levels are Associated with Cognitive Impairment in Parkinson's Disease.

α-Synuclein (α-syn) has a central role in the development of Parkinson's disease (PD). Plasma α-syn has been associated with the presence of cognitive impairment in PD although data have been inconsistent. The aim of this study was to explore the correlation between plasma α-syn levels and cognitive impairment in PD. A total of 53 participants, 26 patients with PD and 27 healthy controls were included in the study. Unified Parkinson's Disease Rating Scale (UPDRS) part Ⅲ and Hohen-Yahr scale (H-Y scale) were used to detect PD severity. The cognitive function was assessed with Montreal Cognitive Assessment (MoCA) scale, Frontal Assessment Battery (FAB), Trail Making Test A (TMT-A), Verbal Function Test (VFT), Clock Drawing Test (CDT), and Rey's Auditory Verbal Learning Test (RAVLT). Enzyme-Linked Immunosorbent Assay (ELISA) method was used to measure α-syn and hemoglobin (Hb) concentration in the plasma samples collected from participants. Plasma α-syn in PD patients was significantly lower than those in the control group (p < 0.01). No associations were found between plasma α-syn and Hb or gender (p > 0.05). The decline in plasma α-syn in PD patients was negatively correlated with disease severity, including UPDRS Ⅲ scores and H-Y scale. Furthermore, lower plasma α-syn was negatively associated with the scores of MoCA, FAB, and RAVLT (immediate recall) scores in PD group. Our data suggest that lower plasma α-syn levels are associated with cognitive decline in PD. Thus, plasma α-syn may be a novel biomarker for patients at risk of cognitive decline.

Decreased plasma α-synuclein in idiopathic Parkinson’s disease patients after adjusting hemolysis factor

Lewy bodies are pathological hallmarks for the diagnosis of Parkinson’s disease, where the core components are composed of aggregated forms of α-synuclein (α-syn). Although α-syn has been investigated as a potential biomarker for PD, its usage has been limited and still remains controversial. An accurate enzyme-linked immunosorbent assay (ELISA) was developed for the detection of α-syn in plasma. The hemolysis score was calculated to eliminate the additive α-syn levels from RBCs. Human plasma samples were collected in heparinized blood tubes from idiopathic Parkinson disease (IPD) and healthy control (HC). Hemolysis score had a strong correlation with the level of plasma α-syn. From the limited set of samples in this preliminary study, decreased α-syn concentrations were observed in patients with IPD in comparison to HC after adjusting for hemolysis factor. Similar results with a commercial ELISA kit were found for measuring α-syn from the same set of samples with lower correlation and the reduced accuracy of diagnosis than the current study. The adjustments for the hemolysis factor would be indispensable, supporting plasma α-syn as a potential surrogate biomarker for distinguishing IPD from HC.

Effect of Times to Blood Processing on the Stability of Blood Proteins Associated with Dementia

Background: The stability of proteins in the collecting tubes after blood draw is critical to the measured concentrations of the proteins. Although the guidelines issued by the Clinical and Laboratory Standards Institute (CLSI) suggest centrifugation should take place within 2 h of drawing blood, it is very difficult to follow these guidelines in hospitals or clinics. It is necessary to study the effect of times to blood processing on the stability of the proteins of interest. Methods: In this work, the plasma proteins of interest were those relevant to dementia, such as amyloid β 1–40 (Aβ_1–40), Aβ_1–42, Tau protein (Tau), and α-synuclein. The times to blood processing after blood draw ranged from 0.5 to 8 h. The storage temperatures of blood were room temperature (approx. 25°C) and 30°C. After storage, blood samples were centrifuged at room temperature to obtain plasma samples. Ultrasensitive immunomagnetic reduction was applied to assay these proteins in the plasma. Results: The levels of plasma Aβ_1–40, Tau, and α-synuclein did not significantly change until 8 h after blood draw when stored at room temperature. Plasma Aβ_1–42 levels did not change significantly after 8 h of storage at room temperature before blood processing. Higher storage temperatures, such as 30°C, for blood samples accelerated the significant variations in the measured concentrations of Aβ_1–40, Tau, and α-synuclein in plasma. Conclusion: According to these results, for clinical practice, it is suggested that blood samples be stored at room temperature for no longer than 4.5 h after blood draw until centrifugation for the assay of dementia biomarkers in plasma.

Peripheral alpha-synuclein levels in patients with genetic and non-genetic forms of Parkinson's disease

BackgroundVariations of α-synuclein levels have been reported in serum and plasma in Parkinson's Disease (PD) Patients. MethodsSerum and plasma were obtained from PD patients without known mutations (GU-PD, n = 124)), carriers of the A53T/G209A point mutation in the α-synuclein gene (SNCA) (n = 29), and respective age-/sex-matched controls. Levels of total α-synuclein were assessed using an in-house ELISA assay. ResultsA statistically significant increase of α-synuclein levels was found in serum, but not plasma, from GU-PD patients compared to healthy controls. A statistically significant decrease of α-synuclein levels was found in serum and plasma from symptomatic A53T mutation carriers compared to healthy controls. Plasma α-synuclein levels were modestly negatively correlated with UPDRS part III score and disease duration in A53T-PD patients. ConclusionIncreased α-synuclein levels in serum of GU-PD patients suggest a systemic deregulation of α-synuclein homeostasis in PD. The opposite results in A53T-PD highlight the complexity of α-synuclein homeostatic regulation in PD, and suggest the possibility of reduced expression of the mutant allele.

Integrated Plasma and Neuroimaging Biomarkers Associated with Motor and Cognition Severity in Parkinson's Disease.

Easily accessible biomarkers are crucial for disease-modifying clinical trials in patients with Parkinson's disease (PD). We investigated integrated plasma and neuroimaging biomarkers correlating with motor and cognitive severity in PD patients. This cross-sectional study enrolled 170 participants (12 controls and 158 PD patients). Plasma α-synuclein and neurofilament light chain (NfL) level, and global and regional cortical thickness (CTh) on brain MRI were analyzed to predict advanced motor stage (Hoehn & Yahr stage ≥3), and PD dementia (PDD, MMSE score <26). Plasma α-synuclein and NfL levels were higher in PD patients than controls (both P < 0.0001 for α-synuclein and NfL). Plasma NfL levels were significantly elevated in patients with advanced motor stage (P = 0.008) or PDD; α-synuclein was elevated in the advanced motor stage group. Global CTh was thinner in patients with PDD than controls (2.33±0.19 mm vs 2.43±0.14 mm, P = 0.06). Among PD patients, higher α-synuclein was associated with thinner limbic CTh, whereas higher NfL was associated with thinner temporal CTh and insular CTh. The accuracy of predicting advanced motor stage using age and sex alone (area under the curve [AUC] 0.63) was significantly improved by the addition of plasma α-synuclein and NfL, and temporal and insula CTh (full model, AUC 0.77, P = 0.004). The accuracy of predicting PDD using age and sex alone (AUC 0.82) increased by incorporating plasma α-synuclein and NfL, and temporal and insula CTh as full model (AUC 0.87, P = 0.047). Integrated plasma and neuroimaging biomarkers reflect both motor and cognitive aspects of PD severity.

Systemic activation of NLRP3 inflammasome and plasma \u03b1-synuclein levels are correlated with motor severity and progression in Parkinson\u2019s disease

BackgroundEmerging evidence indicates that inflammasome-induced inflammation plays a crucial role in the pathogenesis of Parkinson’s disease (PD). Several proteins including α-synuclein trigger the activation of NLRP3 inflammasome. However, few studies examined whether inflammasomes are activated in the periphery of PD patients and their possible value in the diagnosis or tracking of the progress of PD. The aim of this study was to determine the association between inflammasome-induced inflammation and clinical features in PD.MethodsThere were a total of 67 participants, including 43 patients with PD and 24 controls, in the study. Participants received a complete evaluation of motor and non-motor symptoms, including Hoehn and Yahr (H-Y) staging scale. Blood samples were collected from all participants. The protein and mRNA expression levels of inflammasomes subtypes and components in peripheral blood mononuclear cells (PBMCs) were determined using western blotting and RT-qPCR. We applied Meso Scale Discovery (MSD) immunoassay to measure the plasma levels of IL-1β and α-synuclein.ResultsWe observed increased gene expression of NLRP3, ASC, and caspase-1 in PBMCs, and increased protein levels of NLRP3, caspase-1, and IL-1β in PD patients. Plasma levels of IL-1β were significantly higher in patients with PD compared with controls and have a positive correlation with H-Y stage and UPDRS part III scores. Furthermore, plasma α-synuclein levels were also increased in PD patients and have a positive correlation with both UPDRS part III scores and plasma IL-1β levels.ConclusionsOur data demonstrated that the NLRP3 inflammasome is activated in the PBMCs from PD patients. The related inflammatory cytokine IL-1β and total α-synuclein in plasma were increased in PD patients than controls, and both of them presented a positive correlation with motor severity in patients with PD. Furthermore, plasma α-synuclein levels have a positive correlation with IL-1β levels in PD patients. All these findings suggested that the NLRP3 inflammasome activation-related cytokine IL-1β and α-synuclein could serve as non-invasive biomarkers to monitor the severity and progression of PD in regard to motor function.

Clinical and diagnostical values of plasma α-synuclein and melatonin levels in early stages of Parkinson’s disease

Clinical and diagnostical values of plasma α-synuclein and melatonin levels in early stages of Parkinson’s disease