Neurofilament light chain in spinal fluid and plasma in multiple system atrophy: a prospective, longitudinal biomarker study.

PURPOSE: There is a critical need for reliable diagnostic biomarkers as well as surrogate markers of disease progression in multiple system atrophy (MSA). Neurofilament light chain (NfL) has been reported to potentially meet those needs. We therefore sought to explore the value of NfL in plasma (NfL-p) in contrast to cerebrospinal fluid (NfL-c) as a diagnostic marker of MSA, and to assess NfL-p and NfL-c as markers of clinical disease progression. METHODS: Well-characterized patients with early MSA (n = 32), Parkinson's disease (PD; n = 21), and matched controls (CON; n = 15) were enrolled in a prospective, longitudinal study of synucleinopathies with serial annual evaluations. NfL was measured using a high-sensitivity immunoassay, and findings were assessed by disease category and relationship with clinical measures of disease progression. RESULTS: Measurements of NfL-c were highly reproducible across immunoassay platforms (Pearson, r = 0.99), while correlation between NfL-c and -p was only moderate (r = 0.66). NfL was significantly higher in MSA compared with CON and PD; the separation was essentially perfect for NfL-c, but there was overlap, particularly with PD, for NfL-p. While clinical measures of disease severity progressively increased over time, NfL-c and -p remained at stable elevated levels within subjects across serial measurements. Neither change in NfL nor baseline NfL were significantly associated with changes in clinical markers of disease severity. CONCLUSIONS: These findings confirm NfL-c as a faithful diagnostic marker of MSA, while NfL-p showed less robust diagnostic value. The significant NfL elevation in MSA was found to be remarkably stable over time and was not predictive of clinical disease progression.

SCRN1: A cerebrospinal fluid biomarker correlating with tau in Alzheimer's disease.

INTRODUCTION: Secernin-1 (SCRN1) is a neuronal protein that co-localizes with neurofibrillary tangles in Alzheimer's disease (AD), but not with tau inclusions in corticobasal degeneration (CBD), progressive supranuclear palsy (PSP), or Pick's disease. METHODS: We measured SCRN1 concentration in cerebrospinal fluid (CSF) using a novel mass spectrometric parallel reaction monitoring method in three clinical cohorts comprising patients with neurochemically characterized AD (n = 25) and controls (n = 28), clinically diagnosed Parkinson's disease (PD; n = 38), multiple system atrophy (MSA; n = 31), PSP (n = 20), CBD (n = 8), healthy controls (n = 37), and neuropathology-confirmed AD (n = 47). RESULTS: CSF SCRN1 was significantly increased in AD (P < 0.01, fold change = 1.4) compared to controls (receiver operating characteristic area under the curve = 0.78) but not in CBD, PSP, PD, or MSA. CSF SCRN1 positively correlated with CSF total tau (R = 0.78, P = 1.1 × 10-13 ), phosphorylated tau181 (R = 0.64, P = 3.2 × 10-8 ), and Braak stage and negatively correlated with Mini-Mental State Examination score. DISCUSSION: CSF SCRN1 is a candidate biomarker of AD, reflecting tau pathology. HIGHLIGHTS: We developed a parallel reaction monitoring assay to measure secernin-1 (SCRN1) in cerebrospinal fluid (CSF). CSF SCRN1 was increased in Alzheimer's disease compared to healthy controls. CSF SCRN1 remained unchanged in Parkinson's disease, multiple system atrophy, progressive supranuclear palsy, or corticobasal degeneration compared to controls. CSF SCRN1 correlated strongly with CSF phosphorylated tau and total tau. CSF SCRN1 increased across Braak stages and negatively correlated with Mini-Mental State Examination score.

Clinical correlations of cerebrospinal fluid biomarkers including neuron-glia 2 and neurofilament light chain in patients with multiple system atrophy.

BACKGROUND: Multiple system atrophy (MSA) is a progressive neurodegenerative disorder. The usefulness of biomarkers in diagnosing MSA has been recently reported, but few studies have investigated the correlations among cerebrospinal fluid (CSF) biomarkers or the relationship between CSF biomarkers and the clinical parameters of patients with MSA. Thus, this was the aim of our study. METHODS: We performed cross-sectional study of CSF biomarkers in 50 patients with MSA and 20 control subjects. Ten of the patients with MSA were longitudinally followed for a period of 2 ± 1 years (mean ± standard deviation) as a substudy. We quantified CSF biomarkers including α-synuclein (α-syn), ß-amyloid42 (Aß42), total tau (t-tau) and phosphorylated tau (p-tau), neurofilament light chain (NfL), and neuron-glia2 (NG2), and assessed their relationship with clinical parameters (clinical subtypes, motor symptoms, nonmotor symptoms, and disease progression). RESULTS: The levels of CSF α-syn, Aß42, and p-tau were significantly lower, while those of NfL were higher in the patients with MSA than in the control subjects. Importantly, we found the significant elevation of soluble NG2 in the CSF of patients with MSA. CSF NfL showed the optimal diagnostic performance for MSA with levels at baseline significantly associated with longitudinal motor progression. With the exception of t-tau, there were no differences in the levels of CSF biomarkers between the MSA-parkinsonism and MSA-cerebellar subtypes. CONCLUSIONS: Our results suggest CSF levels of NG2 and NfL as possible diagnostic and prognostic biomarkers in MSA. Further study is necessary to validate these findings.

Combined CSF α-SYN RT-QuIC, CSF NFL and midbrain-pons planimetry in degenerative parkinsonisms: From bedside to bench, and back again.

INTRODUCTION: Differential diagnosis between Parkinson's disease (PD) and atypical parkinsonisms (APs: multiple system atrophy[MSA], progressive supranuclear palsy[PSP], corticobasal degeneration[CBD]) remains challenging. Lately, cerebrospinal fluid (CSF) studies of neurofilament light-chain (NFL) and RT-QuIC of alpha-synuclein (α-SYN) have shown promise, but data on their combination with MRI measures is lacking. OBJECTIVE: (1) to assess the combined diagnostic ability of CSF RT-QuIC α-SYN, CSF NFL and midbrain/pons MRI planimetry in degenerative parkinsonisms; (2) to evaluate if biomarker-signatures relate to clinical diagnoses and whether or not unexpected findings can guide diagnostic revision. METHODS: We collected demographic and clinical data and set up α-SYN RT-QuIC at our lab in a cross-sectional cohort of 112 participants: 19 control subjects (CSs), 20PD, 37MSA, 23PSP, and 13CBD cases. We also determined CSF NFL by ELISA and, in 74 participants (10CSs, 9PD, 26MSA, 19PSP, 10CBD), automatized planimetric midbrain/pons areas from 3T-MRI. RESULTS: Sensitivity of α-SYN RT-QuIC for PD was 75% increasing to 81% after revisiting clinical diagnoses with aid of biomarkers. Sensitivity for MSA was 12% but decreased to 9% with diagnostic revision. Specificities were 100% against CSs, and 89% against tauopathies raising to 91% with diagnostic revision. CSF NFL was significantly higher in APs. The combination of biomarkers yielded high diagnostic accuracy (PD vs. non-PD AUC = 0.983; MSA vs. non-MSA AUC = 0.933; tauopathies vs. non-tauopathies AUC = 0.924). Biomarkers-signatures fitted in most cases with clinical classification. CONCLUSIONS: The combination of CSF NFL, CSF RT-QuIC α-SYN and midbrain/pons MRI measures showed high discriminant ability across all groups. Results opposite to expected can assist diagnostic reclassification.

Alterations in Self-Aggregating Neuropeptides in Cerebrospinal Fluid of Patients with Parkinsonian Disorders.

BACKGROUND: Parkinson's disease (PD), progressive supranuclear palsy (PSP), and multiple system atrophy (MSA) present with similar movement disorder symptoms but distinct protein aggregates upon pathological examination. OBJECTIVE: Discovery and validation of candidate biomarkers in parkinsonian disorders for differential diagnosis of subgroup molecular etiologies. METHODS: Untargeted liquid chromatography (LC)-mass spectrometry (MS) proteomics was used for discovery profiling in cerebral spinal fluid (CSF) followed by LC-MS/MS based multiple reaction monitoring for validation of candidates. We compared clinical variation within the parkinsonian cohort including PD subgroups exhibiting tremor dominance (TD) or postural instability gait disturbance and those with detectable leukocytes in CSF. RESULTS: We have identified candidate peptide biomarkers and validated related proteins with targeted quantitative multiplexed assays. Dopamine-drug naïve patients at first diagnosis exhibit reduced levels of signaling neuropeptides, chaperones, and processing proteases for packaging of self-aggregating peptides into dense core vesicles. Distinct patterns of biomarkers were detected in the parkinsonian disorders but were not robust enough to offer a differential diagnosis. Different biomarker changes were detected in male and female patients with PD. Subgroup specific candidate biomarkers were identified for TD PD and PD patients with leukocytes detected in CSF. CONCLUSION: PD, MSA, and PSP exhibit overlapping as well as distinct protein biomarkers that suggest specific molecular etiologies. This indicates common sensitivity of certain populations of selectively vulnerable neurons in the brain, and distinct therapeutic targets for PD subgroups. Our report validates a decrease in CSF levels of self-aggregating neuropeptides in parkinsonian disorders and supports the role of native amyloidogenic proteins in etiologies of neurodegenerative diseases.

Cerebrospinal Fluid Metabolome in Parkinson's Disease and Multiple System Atrophy.

Parkinson's disease (PD) and multiple system atrophy (MSA) belong to the neurodegenerative group of synucleinopathies; differential diagnosis between PD and MSA is difficult, especially at early stages, owing to their clinical and biological similarities. Thus, there is a pressing need to identify metabolic biomarkers for these diseases. The metabolic profile of the cerebrospinal fluid (CSF) is reported to be altered in PD and MSA; however, the altered metabolites remain unclear. We created a single network with altered metabolites in PD and MSA based on the literature and assessed biological functions, including metabolic disorders of the nervous system, inflammation, concentration of ATP, and neurological disorder, through bioinformatics methods. Our in-silico prediction-based metabolic networks are consistent with Parkinsonism events. Although metabolomics approaches provide a more quantitative understanding of biochemical events underlying the symptoms of PD and MSA, limitations persist in covering molecules related to neurodegenerative disease pathways. Thus, omics data, such as proteomics and microRNA, help understand the altered metabolomes mechanism. In particular, integrated omics and machine learning approaches will be helpful to elucidate the pathological mechanisms of PD and MSA. This review discusses the altered metabolites between PD and MSA in the CSF and omics approaches to discover diagnostic biomarkers.

Cerebrospinal fluid and plasma distribution of anti-α-synuclein IgMs and IgGs in multiple system atrophy and Parkinson's disease.

INTRODUCTION: Ubiquitous naturally occurring autoantibodies (nAbs) against alpha-synuclein (α-syn) may play important roles in the pathogenesis of Multiple System Atrophy (MSA) and Parkinson's disease (PD). Recently, we reported reduced high-affinity/avidity anti-α-syn nAbs levels in plasma from MSA and PD patients, along with distinct inter-group immunoglobulin (Ig)G subclass distributions. The extent to which these observations in plasma may reflect corresponding levels in the cerebrospinal fluid (CSF) is unknown. METHODS: Using competitive and indirect ELISAs, we investigated the affinity/avidity of CSF anti-α-syn nAbs as well as the CSF and plasma distribution of IgG subclasses and IgM nAbs in a cross-sectional cohort of MSA and PD patients. RESULTS: Repertoires of high-affinity/avidity anti-α-syn IgG nAbs were reduced in CSF samples from MSA and PD patients compared to controls. Furthermore, anti-α-syn IgM nAb levels were relatively lower in CSF and plasma from MSA patients but were reduced only in plasma from PD patients. Interestingly, anti-α-syn IgG subclasses presented disease-specific profiles both in CSF and plasma. Anti-α-syn IgG1, IgG2 and IgG3 levels were relatively increased in CSF of MSA patients, whereas PD patients showed increased anti-α-syn IgG2 and reduced anti-α-syn IgG4 levels. CONCLUSIONS: Differences in the plasma/CSF distribution of anti-α-syn nAbs seem to be a common feature of synucleinopathies. Our data add further support to the notion that MSA and PD patients may have compromised immune reactivity towards α-syn. The differing α-syn-specific systemic immunological responses may reflect their specific disease pathophysiologies. These results are encouraging for further investigation of these immunological mechanisms in neurodegenerative diseases.

Alpha-Synuclein Oligomers and Neurofilament Light Chain Predict Phenoconversion of Pure Autonomic Failure.

OBJECTIVE: To explore the role of alpha-synuclein (αSyn) oligomers and neurofilament light chain (NfL) in cerebrospinal fluid (CSF) of patients with pure autonomic failure (PAF) as markers of future phenoconversion to multiple system atrophy (MSA). METHODS: Well-characterized patients with PAF (n = 32) were enrolled between June 2016 and February 2019 at Mayo Clinic Rochester and followed prospectively with annual visits to determine future phenoconversion to MSA, Parkinson's disease (PD), or dementia with Lewy bodies (DLB). ELISA was utilized to measure NfL and protein misfolding cyclic amplification (PMCA) to detect αSyn oligomers in CSF collected at baseline. RESULTS: Patients were followed for a median of 3.9 years. Five patients converted to MSA, 2 to PD, and 2 to DLB. NfL at baseline was elevated only in patients who later developed MSA, perfectly separating those from future PD and DLB converters as well as non-converters. ASyn-PMCA was positive in all but two cases (94%). The PMCA reaction was markedly different in five samples with maximum fluorescence and reaction kinetics previously described in MSA patients; all of these patients later developed MSA. INTERPRETATION: αSyn-PMCA is almost invariably positive in the CSF of patients with PAF establishing this condition as α-synucleinopathy. Both NfL and the magnitude and reaction kinetics of αSyn PMCA faithfully predict which PAF patients will eventually phenoconvert to MSA. This finding has important implications not only for prognostication, but also for future trials of disease modifying therapies, allowing for differentiation of MSA from Lewy body synucleinopathies before motor symptoms develop. ANN NEUROL 2021;89:1212-1220.

Differential abnormalities of cerebrospinal fluid dopaminergic versus noradrenergic indices in synucleinopathies.

The synucleinopathies Parkinson's disease (PD), multiple system atrophy (MSA), and pure autonomic failure (PAF) are characterized by intra-cytoplasmic deposition of the protein alpha-synuclein and by catecholamine depletion. PAF, which manifests with neurogenic orthostatic hypotension (nOH) and no motor signs of central neurodegeneration, can evolve into PD+nOH. The cerebrospinal fluid (CSF) levels of catecholamine metabolites may indicate central catecholamine deficiency in these synucleinopathies, but the literature is inconsistent and incomplete. In this retrospective cohort study we reviewed data about CSF catecholamines, the dopamine metabolites 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), and the norepinephrine metabolites 3,4-dihydroxyphenylglycol (DHPG) and 3-methoxy-4-hydroxyphenylglycol (MHPG). The compounds were measured in 36 patients with PD, 37 patients with MSA, and 19 patients with PAF and in 38 controls. Compared to the control group, the PD, MSA, and PAF groups had decreased CSF MHPG (p < .0001 each by Dunnett's post hoc test), DHPG (p = .004; p < .0001; p < .0001) and norepinephrine (p = .017; p = .0003; p = .044). CSF HVA and DOPAC were decreased in PD (p < .0001 each) and MSA (p < .0001 each) but not in PAF. The three synucleinopathies therefore have in common in vivo evidence of central noradrenergic deficiency but differ in the extents of central dopaminergic deficiency-prominent in PD and MSA, less apparent in PAF. Data from putamen 18 F-DOPA and cardiac 18 F-dopamine neuroimaging in the same patients, post-mortem tissue catecholamines in largely separate cohorts, and review of the neuropathology literature fit with these distinctions. The results suggest a 'norepinephrine first' ascending pathogenetic sequence in synucleinopathies, with degeneration of pontine locus ceruleus noradrenergic neurons preceding the loss of midbrain substantia nigra dopaminergic neurons.

Predictors of Conversion to α-Synucleinopathy Diseases in Idiopathic Rapid Eye Movement Sleep Behavior Disorder.

BACKGROUND: Idiopathic rapid eye movement sleep behavior disorder (iRBD) often precedes the development of α-synucleinopathy diseases. OBJECTIVE: We aimed to assess the predictive value of clinical variables and biomarkers for the early development of α-synucleinopathy diseases in subjects with iRBD. METHODS: 56 patients with RBD Screening Questionnaire (RBDSQ) scores ≥5 at baseline and subsequent visit were enrolled as probable iRBD from the Parkinson's Progression Markers Initiative (PPMI) database. Baseline clinical data and biomarkers were analyzed. The endpoint was defined as disease progression to α-synucleinopathy diseases. Cox proportional hazard and Kaplan-Meier analyses were used to evaluate the predictive values of the indicators. RESULTS: During a mean follow-up duration of 5.1 years, 15 of 56 patients (26.8%) developed α-synucleinopathy diseases. Baseline clinical variables, including University of Pennsylvania Smell Identification Test (UPSIT, HR = 26.18, p = 0.004), 15-item Geriatric Depression Scale (GDS, HR = 14.26, p = 0.001), Montreal Cognitive Assessment (MoCA, HR = 3.56, p = 0.025), and Hopkins Verbal Learning Test Total recall (HVLT-TR, HR = 3.70, p = 0.014); genotype status of TMEM175 (HR = 3.74, p = 0.017), SCN3A (HR = 5.81, p = 0.022) and NUCKS1 (HR = 0.342, p = 0.049); ratio of phosphorylated tau to total tau (p-tau/t-tau, HR = 8.36, p = 0.001) in cerebrospinal fluid; and gray matter atrophy in inferior frontal gyrus (IFG, HR = 15.49, p = 0.001) were associated with phenoconversion to α-synucleinopathy diseases. A model combined the three independent variables (UPSIT, TMEM175 and gray matter atrophy in IFG) exhibited significantly improved predictive performance. CONCLUSION: For patients with iRBD, progression to α-synucleinopathy diseases can be predicted with good accuracy using a model combining clinical variables and biomarkers, which could form a basis for future disease prevention.

Cerebrospinal fluid myelin basic protein is elevated in multiple system atrophy.

INTRODUCTION: Parkinson's disease (PD) and multiple system atrophy (MSA) have overlapping symptoms, challenging an early diagnosis. Diagnostic accuracy is important because PD and MSA have a different prognosis and response to treatment. Here, we aimed to evaluate the diagnostic value of brain-specific structural proteins in cerebrospinal fluid (CSF) of PD and MSA patients, as well as their association with cognitive decline. METHODS: CSF samples were collected from patients with clear signs of parkinsonism, but with uncertain diagnosis at the time of inclusion. Clinical diagnoses of PD (n = 55) and MSA (n = 22) were established after 3 and 10 years of follow-up and re-evaluated after 12 years, according to the most updated clinical criteria. CSF from controls (n = 118) was studied for comparison. Neuron-specific enolase (NSE), glial fibrillary acidic protein (GFAP), S100 calcium-binding protein B (S100B) and myelin basic protein (MBP) levels in CSF were measured using ELISA. Protein levels were also correlated with cognitive decline, i.e. worsening of the mini mental state examination (MMSE) over a period of three years. RESULTS: MBP concentrations were increased in MSA compared to PD and controls (p < 0.005) and could differentiate MSA and PD with high accuracy (AUC = 0.781; p < 0.001). Concentrations of MPB, GFAP and S100B, but not NSE, were significantly elevated in PD patients compared to controls (p = 0.05). None of the brain-specific structural proteins correlated with MMSE progression. CONCLUSIONS: Our results demonstrate that MBP differentiates PD from MSA at early stages of the disease, indicating that demyelination and axonal damage may already occur in early stages of MSA.

Alpha-Synuclein Oligomers and Neurofilament Light Chain in Spinal Fluid Differentiate Multiple System Atrophy from Lewy Body Synucleinopathies.

OBJECTIVE: To explore the role of alpha-synuclein (αSyn) oligomers and neurofilament light chain (NFL) in cerebrospinal fluid (CSF) as markers of early multiple system atrophy (MSA) and to contrast findings with Lewy body synucleinopathies. METHODS: In a discovery cohort of well-characterized early MSA patients (n = 24) and matched healthy controls (CON, n = 14), we utilized enzyme-linked immunosorbent assay to measure NFL and protein misfolding cyclic amplification (PMCA) to detect αSyn oligomers in CSF. We confirmed findings in a separate prospectively enrolled cohort of patients with early MSA (n = 38), Parkinson disease (PD, n = 16), and dementia with Lewy bodies (DLB, n = 13), and CON subjects (n = 15). RESULTS: In the discovery cohort, NFL was markedly elevated in MSA patients, with perfect separation from CON. αSyn-PMCA was nonreactive in all CON, whereas all MSA samples were positive. In the confirmatory cohort, NFL again perfectly separated MSA from CON, and was significantly lower in PD and DLB compared to MSA. PMCA was again nonreactive in all CON, and positive in all but 2 MSA cases. All PD and all but 2 DLB samples were also positive for αSyn aggregates but with markedly different reaction kinetics from MSA; aggregation occurred later, but maximum fluorescence was higher, allowing for perfect separation of reactive samples between MSA and Lewy body synucleinopathies. INTERPRETATION: NFL and αSyn oligomers in CSF faithfully differentiate early MSA not only from CON but also from Lewy body synucleinopathies. The findings support the role of these markers as diagnostic biomarkers, and have important implications for understanding pathophysiologic mechanisms underlying the synucleinopathies. ANN NEUROL 2020;88:503-512.

Alpha-synuclein Levels in the Differential Diagnosis of Lewy Bodies Dementia and Other Neurodegenerative Disorders: A Meta-analysis.

SUBJECTIVES: Lewy body dementia (LBD) is the second most common type of neurodegenerative dementia after Alzheimer disease (AD). It is characterized by the accumulation of Lewy bodies and Lewy neurites which are composed of aggregated phosphorylated alpha-synuclein, which is a presynaptic neuronal protein genetically and neuropathologically linked to Parkinson disease and to LBD. Alpha-synuclein is thought to contribute to LBD pathogenesis and to linked to disruption of cellular homeostasis and neuronal death, through effects on various intracellular targets, including synaptic function. METHODS: In the present study, we did a meta-analysis on the reliability of alpha-synuclein levels in the cerebrospinal fluid (CSF) for the discrimination between LBD and other neurodegenerative disorders including AD, Parkinson disease (PD) dementia, progressive supranuclear palsy (PSP), multiple system atrophy (MSA) and frontotemporal dementia (FTD). RESULTS: CSF alpha-synuclein levels were significantly different in LBD compared with AD, but no statistical difference was found between LBD, and dementia in PD, MSA, PSP, and FTD. CONCLUSION: Alpha-synuclein levels in the CSF can be used for the discrimination between LBD and AD, but not LBD and other neurodegenerative disorders such as dementia in PD, MSA, FTD, and PSP.

Discriminating α-synuclein strains in Parkinson's disease and multiple system atrophy.

Synucleinopathies are neurodegenerative diseases that are associated with the misfolding and aggregation of α-synuclein, including Parkinson's disease, dementia with Lewy bodies and multiple system atrophy1. Clinically, it is challenging to differentiate Parkinson's disease and multiple system atrophy, especially at the early stages of disease2. Aggregates of α-synuclein in distinct synucleinopathies have been proposed to represent different conformational strains of α-synuclein that can self-propagate and spread from cell to cell3-6. Protein misfolding cyclic amplification (PMCA) is a technique that has previously been used to detect α-synuclein aggregates in samples of cerebrospinal fluid with high sensitivity and specificity7,8. Here we show that the α-synuclein-PMCA assay can discriminate between samples of cerebrospinal fluid from patients diagnosed with Parkinson's disease and samples from patients with multiple system atrophy, with an overall sensitivity of 95.4%. We used a combination of biochemical, biophysical and biological methods to analyse the product of α-synuclein-PMCA, and found that the characteristics of the α-synuclein aggregates in the cerebrospinal fluid could be used to readily distinguish between Parkinson's disease and multiple system atrophy. We also found that the properties of aggregates that were amplified from the cerebrospinal fluid were similar to those of aggregates that were amplified from the brain. These findings suggest that α-synuclein aggregates that are associated with Parkinson's disease and multiple system atrophy correspond to different conformational strains of α-synuclein, which can be amplified and detected by α-synuclein-PMCA. Our results may help to improve our understanding of the mechanism of α-synuclein misfolding and the structures of the aggregates that are implicated in different synucleinopathies, and may also enable the development of a biochemical assay to discriminate between Parkinson's disease and multiple system atrophy.

Inflammation biomarker discovery in Parkinson's disease and atypical parkinsonisms.

BACKGROUND: Parkinson's disease (PD) and atypical parkinsonisms (APD) have overlapping symptoms challenging an early diagnosis. Diagnostic accuracy is important because PD and APD have different prognosis and response to treatment. We aimed to identify diagnostic inflammatory biomarkers of PD and APD in cerebrospinal fluid (CSF) using the multiplex proximity extension assay (PEA) technology and to study possible correlations of biomarkers with disease progression. METHODS: CSF from a longitudinal cohort study consisting of PD and APD patients (PD, n = 44; multiple system atrophy (MSA), n = 14; vascular parkinsonism (VaP), n = 9; and PD with VaP, n = 7) and controls (n = 25) were analyzed. RESULTS: Concentrations of CCL28 were elevated in PD compared to controls (p = 0.0001). Five other biomarkers differentiated both MSA and PD from controls (p < 0.05) and 10 biomarkers differentiated MSA from controls, of which two proteins, i.e. beta nerve growth factor (ß-NGF) and Delta and Notch like epidermal growth factor-related receptor (DNER), were also present at lower levels in MSA compared to PD (both p = 0.032). Two biomarkers (MCP-1 and MMP-10) positively correlated with PD progression (rho > 0.650; p < 0.01). CONCLUSIONS: PEA technique identified potential new CSF biomarkers to help to predict the prognosis of PD. Also, we identified new candidate biomarkers to distinguish MSA from PD.

Cerebrospinal fluid cytokines in multiple system atrophy: A cross-sectional Catalan MSA registry study.

INTRODUCTION: Neuroinflammation is a potential player in neurodegenerative conditions, particularly the aggressive ones, such as multiple system atrophy (MSA). Previous reports on cytokine levels in MSA using serum or cerebrospinal fluid (CSF) have been inconsistent, including small samples and a limited number of cytokines, often without comparison to Parkinson's disease (PD), a main MSA differential diagnosis. METHODS: Cross-sectional study of CSF levels of 38 cytokines using a multiplex assay in 73 participants: 39 MSA patients (19 with parkinsonian type [MSAp], 20 with cerebellar type [MSAc]; 31 probable, 8 possible), 19 PD patients and 15 neurologically unimpaired controls. None of the participants was under non-steroidal anti-inflammatory drugs at the time of the lumbar puncture. RESULTS: There were not significant differences in sex and age among participants. In global non-parametric comparisons FDR-corrected for multiple comparisons, CSF levels of 5 cytokines (FGF-2, IL-10, MCP-3, IL-12p40, MDC) differed among the three groups. In pair-wise FDR-corrected non-parametric comparisons 12 cytokines (FGF-2, eotaxin, fractalkine, IFN-α2, IL-10, MCP-3, IL-12p40, MDC, IL-17, IL-7, MIP-1ß, TNF-α) were significantly higher in MSA vs. non-MSA cases (PD + controls pooled together). Of these, MCP-3 and MDC were the most significant ones, also differed in MSA vs. PD, and were significant MSA-predictors in binary logistic regression models and ROC curves adjusted for age. CSF levels of fractalkine and MIP-1α showed a strong and significant positive correlation with UMSARS-2 scores. CONCLUSION: Increased CSF levels of cytokines such as MCP-3, MDC, fractalkine and MIP-1α deserve consideration as potential diagnostic or severity biomarkers of MSA.

Intrathecal administration of autologous mesenchymal stem cells in multiple system atrophy.

OBJECTIVE: This phase I/II study sought to explore intrathecal administration of mesenchymal stem cells (MSCs) as therapeutic approach to multiple system atrophy (MSA). METHODS: Utilizing a dose-escalation design, we delivered between 10 and 200 million adipose-derived autologous MSCs intrathecally to patients with early MSA. Patients were closely followed with clinical, laboratory, and imaging surveillance. Primary endpoints were frequency and type of adverse events; key secondary endpoint was the rate of disease progression assessed by the Unified MSA Rating Scale (UMSARS). RESULTS: Twenty-four patients received treatment. There were no attributable serious adverse events, and injections were generally well-tolerated. At the highest dose tier, 3 of 4 patients developed low back/posterior leg pain, associated with thickening/enhancement of lumbar nerve roots. Although there were no associated neurologic deficits, we decided that dose-limiting toxicity was reached. A total of 6 of 12 patients in the medium dose tier developed similar, but milder and transient discomfort. Rate of progression (UMSARS total) was markedly lower compared to a matched historical control group (0.40 ± 0.59 vs 1.44 ± 1.42 points/month, p = 0.004) with an apparent dose-dependent effect. CONCLUSIONS: Intrathecal MSC administration in MSA is safe and well-tolerated but can be associated with a painful implantation response at high doses. Compelling dose-dependent efficacy signals are the basis for a planned placebo-controlled trial. CLASSIFICATION OF EVIDENCE: This phase I/II study provides Class IV evidence that for patients with early MSA, intrathecal MSC administration is safe, may result in a painful implantation response at high doses, and is associated with dose-dependent efficacy signals.

CSF biomarkers distinguish idiopathic normal pressure hydrocephalus from its mimics.

OBJECTIVE: To examine the differential diagnostic significance of cerebrospinal fluid (CSF) biomarkers reflecting Alzheimer's disease-related amyloid ß (Aß) production and aggregation, cortical neuronal damage, tau pathology, damage to long myelinated axons and astrocyte activation, which hypothetically separates patients with idiopathic normal pressure hydrocephalus (iNPH) from patients with other neurodegenerative disorders. METHODS: The study included lumbar CSF samples from 82 patients with iNPH, 75 with vascular dementia, 70 with Parkinson's disease, 34 with multiple system atrophy, 34 with progressive supranuclear palsy, 15 with corticobasal degeneration, 50 with Alzheimer's disease, 19 with frontotemporal lobar degeneration and 54 healthy individuals (HIs). We analysed soluble amyloid precursor protein alpha (sAPPα) and beta (sAPPß), Aß species (Aß38, Aß40 and Aß42), total tau (T-tau), phosphorylated tau, neurofilament light and monocyte chemoattractant protein 1 (MCP-1). RESULTS: Patients with iNPH had lower concentrations of tau and APP-derived proteins in combination with elevated MCP-1 compared with HI and the non-iNPH disorders. T-tau, Aß40 and MCP-1 together yielded an area under the curve of 0.86, differentiating iNPH from the other disorders. A prediction algorithm consisting of T-tau, Aß40 and MCP-1 was designed as a diagnostic tool using CSF biomarkers. CONCLUSIONS: The combination of the CSF biomarkers T-tau, Aß40 and MCP-1 separates iNPH from cognitive and movement disorders with good diagnostic sensitivity and specificity. This may have important implications for diagnosis and clinical research on disease mechanisms for iNPH.

Elevated serum ferritin level as a predictor of reduced survival in patients with sporadic amyotrophic lateral sclerosis in China: a retrospective study.

Objective: The objective of this study was to compare iron metabolic variables in the serum and cerebrospinal fluid (CSF) of patients with sporadic amyotrophic lateral sclerosis (sALS) with those of patients with multiple system atrophy (MSA) and control subjects. We also assessed the correlations of these variables with sALS progression and severity and estimated their roles in predicting prognosis. Methods: We retrospectively collected iron metabolic parameters, including serum levels of iron, ferritin, transferrin levels and total iron binding capacity and the CSF level of ferritin, from 435 sALS patients, 176 MSA patients and 431 control subjects. Results: Serum ferritin levels were significantly higher in the sALS group compared with the MSA and control groups in both males (p = 0.001 and p < 0.0001, respectively) and females (p = 0.034 and p < 0.0001, respectively). However, serum transferrin levels were significantly lower in females of the sALS group compared with the MSA (p = 0.016) and control (p = 0.015) groups. The CSF ferritin level and the serum levels of total iron binding capacity and iron were similar among the sALS, MSA and control groups. Survival analysis demonstrated that higher serum ferritin levels were predictors of reduced survival of sALS patients. No correlations between iron metabolic variables and clinical parameters were found. Conclusion: An elevated serum ferritin level is associated with reduced survival of sALS patients. However, the levels of iron metabolic parameters were not associated with clinical deterioration or disease severity at diagnosis.

Antibody-based methods for the measurement of α-synuclein concentration in human cerebrospinal fluid - method comparison and round robin study.

α-Synuclein is the major component of Lewy bodies and a candidate biomarker for neurodegenerative diseases in which Lewy bodies are common, including Parkinson's disease and dementia with Lewy bodies. A large body of literature suggests that these disorders are characterized by reduced concentrations of α-synuclein in cerebrospinal fluid (CSF), with overlapping concentrations compared to healthy controls and variability across studies. Several reasons can account for this variability, including technical ones, such as inter-assay and inter-laboratory variation (reproducibility). We compared four immunochemical methods for the quantification of α-synuclein concentration in 50 unique CSF samples. All methods were designed to capture most of the existing α-synuclein forms in CSF ('total' α-synuclein). Each of the four methods showed high analytical precision, excellent correlation between laboratories (R2 0.83-0.99), and good correlation with each other (R2 0.64-0.93), although the slopes of the regression lines were different between the four immunoassays. The use of common reference CSF samples decreased the differences in α-synuclein concentration between detection methods and technologies. Pilot data on an immunoprecipitation mass spectrometry (IP-MS) method is also presented. Our results suggest that the four immunochemical methods and the IP-MS method measure similar forms of α-synuclein and that a common reference material would allow harmonization of results between immunoassays.