Search

Cerebrospinal fluid ( CSF) has been extensively studied to explore biochemical alterations in subjects with neurodegenerative disorders. In Alzheimer's disease, levels of increased CSF tau protein and decreased levels of β-amyloid 1-42 (Aβ42) have been shown to correlate with brain plaque formation and tangle pathology. Intracellular Lewy inclusions containing aggregated α-synuclein (α-syn) represent a pathological hallmark of Parkinson's disease ( PD). In most - but not all - studies published to date total CSF α-syn concentrations have been found to be decreased in disorders related to α-syn pathology, that is, PD, dementia with Lewy bodies and multiple system atrophy. However, these reports show extensive signal overlap among tested individuals, thereby diminishing its potential for routine use in clinical practice. To investigate potential biological (i.e., non-technical) confounders of reported CSF levels for α-syn, Aβ42, and tau in PD and related disorders, we carried out a methodical review of known factors that underlie signal variability and speculate on those that have not yet been tested. We discuss several biological factors, such as neuropathology, demographics, clinical phenotype, progression and duration of disease, concomitant illnesses and, last but not least, pharmacotherapy, which in isolation or combination can substantially alter values for CSF proteins of interest. Enhanced implementation of standardized clinical protocols, streamlined operating procedures, and further progress in the development of validated assays for CSF proteins have the potential to (i) inform us as to the pathogenesis of disease, (ii) support the laboratory-based diagnosis for symptomatic subjects in the future, and (iii) facilitate breakthrough therapies to alter the course of neurodegenerative disorders, such as PD and Alzheimer's disease. [ABSTRACT FROM AUTHOR]

ABSTRACT Parkinson's disease is characterized by the pathological aggregation of Alpha-synuclein. The dual-hit hypothesis proposed by Braak implicates the enteric nervous system as an initial site of α-synuclein aggregation with subsequent spread to the central nervous system. Regional variations in the spatial pattern or levels of α-synuclein along the enteric nervous system could have implications for identifying sites of onset of this pathogenic cascade. We performed immunohistochemical staining for α-synuclein on gastrointestinal tissue from patients with no history of neurological disease using the established LB509 antibody and a new clone, MJFR1, characterized for immunohistochemistry here. We demonstrate that the vermiform appendix is particularly enriched in α-synuclein-containing axonal varicosities, concentrated in its mucosal plexus rather than the classical submucosal and myenteric plexuses. Unexpectedly, intralysosomal accumulations of α-synuclein were detected within mucosal macrophages of the appendix. The abundance and accumulation of α-synuclein in the vermiform appendix implicate it as a candidate anatomical locus for the initiation of enteric α-synuclein aggregation and permits the generation of testable hypotheses for Parkinson's disease pathogenesis. © 2013 International Parkinson and Movement Disorder Society [ABSTRACT FROM AUTHOR]

Heterozygous mutations in the glucocerebrosidase gene (GBA1) are associated with increased risk for α-synuclein aggregation disorders ('synucleinopathies'), which include Parkinson's disease (PD) and dementia with Lewy bodies (DLB). Homozygous GBA1 mutations lead to reduced GBA1 lysosomal activity underlying three variants of Gaucher disease (GD). Despite the wealth of clinical and genetic evidence supporting the association between mutant genotypes and synucleinopathy risk, the precise mechanisms by which GBA1 mutations lead to PD and DLB remain unclear. Here, we summarize recent findings that highlight the complexity of this pathogenetic link. In neural cells, both gain and loss of function mechanisms, as conferred by mutant GBA1 expression and activity loss, respectively, seem to promote aberrant α-synuclein processing. In addition, we draw attention to recent insights gleaned from GD animal models regarding axonal pathology, brain inflammation and memory dysfunction. From a translational perspective, we discuss the concepts of neural enzyme replacement therapy and pharmacological agents as potential treatment strategies for GBA1-associated synucleinopathies. Finally, we touch on the issue whether aberrant α-synuclein species may coregulate GBA1 activity in the vertebrate brain, thereby providing a reverse link, i.e., between an important synucleinopathy risk factor and the enzyme's lysosomal function. In summary, several leads connecting GBA1 mutations with α-synuclein misprocessing have emerged as potential targets for the treatment of GBA1-related synucleinopathies, and possibly, for non-GBA1-associated neurodegenerative diseases. Copyright © 2012 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Mutations in the synaptic protein α-synuclein cause rare genetic forms of Parkinson's disease. α-Synuclein is thought to play a critical role in more common sporadic cases of Parkinson's disease as well because the protein aggregates in the hallmark intraneuronal inclusions of the disorder, Lewy bodies. To test the role of protein aggregation in the pathogenesis of Parkinson's disease, we expressed a form of α-synuclein with a deletion of amino acids 71-82 that is unable to aggregate in vitro in a transgenic Drosophila model of the disorder. We found no evidence of large aggregates or oligomeric species of α-synuclein in these animals and no loss of tyrosine hydroxylase-positive neurons. We also expressed a truncated form of α-synuclein that has enhanced ability to aggregate in vitro. This truncated form of α-synuclein showed increased aggregation into large inclusions bodies, increased accumulation of high molecular weight α-synuclein species, and demonstrated enhanced neurotoxicity in vivo. Our findings thus support a critical role for aggregation of α-synuclein in mediating toxicity to dopaminergic neurons in vivo, although the precise role each aggregated form of α-synuclein plays in neurotoxicity remains to be determined. [ABSTRACT FROM AUTHOR]

Abstract: The need for improved diagnostic accuracy and markers of progression in neurodegenerative diseases motivates the identification of objective biomarkers as well as optimized assays for their quantification. Several potential marker candidates for Parkinson’s disease (PD) in cerebrospinal fluid have been identified. These include α-synuclein, a major constituent of the intracellular aggregates. We give a general overview and details of our experience in converting established enzyme-linked immunoabsorbent assays (for α-synuclein and other proteins) onto an electrochemiluminescence-based platform as well as considerations on multiplexing different assays for PD. [Copyright &y& Elsevier]

Despite growing research efforts, no reliable biomarker currently exists for the diagnosis and prognosis of multiple system atrophy (MSA). Such biomarkers are urgently needed to improve diagnostic accuracy, prognostic guidance and also to serve as efficacy measures or surrogates of target engagement for future clinical trials. We here review candidate fluid biomarkers for MSA and provide considerations for further developments and harmonization of standard operating procedures. A PubMed search was performed until April 24, 2015 to review the literature with regard to candidate blood and cerebrospinal fluid (CSF) biomarkers for MSA. Abstracts of 1760 studies were retrieved and screened for eligibility. The final list included 60 studies assessing fluid biomarkers in patients with MSA. Most studies have focused on alpha-synuclein, markers of axonal degeneration or catecholamines. Their results suggest that combining several CSF fluid biomarkers may be more successful than using single markers, at least for the diagnosis. Currently, the clinically most useful markers may comprise a combination of the light chain of neurofilament (which is consistently elevated in MSA compared to controls and Parkinson’s disease), metabolites of the catecholamine pathway and proteins such as α-synuclein, DJ-1 and total-tau. Beyond future efforts in biomarker discovery, the harmonization of standard operating procedures will be crucial for future success. [ABSTRACT FROM AUTHOR]

Abstract: Several studies demonstrated reduced CSF α-synuclein values in patients with advanced Parkinson''s disease (PD). Values in drug-naïve PD subjects and healthy controls (HC) have not yet been reported. We measured CSF values including α-synuclein in a cohort of 78 previously untreated PD patients and 48 HC subjects. Measurements of total α-synuclein concentrations were performed using two independently operated immunoassays, i.e., one academia-based and previously validated (ELISA 1), the other industry-based, renewable and commercially available (ELISA 2). Mean values for CSF α-synuclein were significantly lower in de novo PD patients when compared to HC subjects, as demonstrated by both assays (ELISA 1, p =0.049; ELISA 2, p =0.005; combined, p =0.002). Using the renewable ELISA 2, CSF α-synuclein concentrations of 1884.31pg/ml or less showed a sensitivity of 0.91 and a specificity of 0.25 for the diagnosis of Parkinson''s disease. The corresponding area-under-the-curve value was 0.65 (confidence interval, 0.554–0.750), which was statistically significant (p =0.004). Total CSF α-synuclein is reduced early in the course of Parkinson''s disease, as measured by two independent ELISA platforms at the time of enrolment, and this reduction appears independent from drug treatment. Follow-up investigations will determine the usefulness of CSF α-synuclein values as markers of progression in individual subjects. [Copyright &y& Elsevier]

Abstract: Because accumulation of α-synuclein (αS) in the brain is a hallmark of Parkinson disease (PD) and related disorders, we examined its occurrence in human cerebrospinal fluid (CSF). Following affinity enrichment and trypsin digestion of CSF collected from a neurologically healthy donor, we identified several αS-derived peptides by mass spectrometry. The concentration of αS amounted to <0.001% of the CSF proteome. We then built, validated and optimized a sandwich-type, enzyme-linked immunoadsorbent assay (ELISA) to measure total αS levels in unconcentrated CSF. In a cross-sectional study of 100 living donors, we examined cell-free CSF samples from subjects clinically diagnosed with advanced PD, dementia with Lewy bodies (DLB), Alzheimer disease (AD), and a group of non-neurodegenerative disease controls (NCO). In these four groups the CSF αS concentrations ranged from 0.8 to 16.2 pg/μl. Mean CSF αS values were lower in donors with a primary synucleinopathy (PD, DLB: n =57) than in the other two groups (AD, NCO: n =35; p =0.025). By contrast, living Creutzfeldt–Jakob disease patients showed markedly elevated CSF αS levels (n =8; mean, 300 pg/μl; p <0.001). Our results unequivocally confirm the presence of αS in adult human CSF. In a first feasibility study employing a novel ELISA, we found relatively low CSF αS concentrations in subjects with parkinsonism linked to synucleinopathy, PD and DLB. In definite prion disease cases, we recorded a marked rise in total CSF αS resulting from rapid cell death. Our results will likely aid future biomarker explorations in neurodegenerative conditions and facilitate target validation studies. [Copyright &y& Elsevier]

Abstract: There is ample biochemical, pathological, and genetic evidence that the metabolism of α-synuclein (α-syn) plays a crucial role in the pathogenesis of Parkinson disease (PD). To examine whether quantification of α-syn in cerebrospinal fluid (CSF) is potentially informative in the diagnosis of PD, we developed a specific ELISA system and measured the concentration of α-syn in CSF from 33 patients with PD (diagnosed according to UK PD Society Brain Bank criteria) and 38 control subjects including 9 neurologically healthy individuals. We found that PD patients had significantly lower α-syn levels in their CSF than the control groups (p <0.0001) even after adjusting for gender and age. Age was independently associated with lower α-syn levels. Logistic regression analysis showed that reduction in CSF α-syn served as a significant predictor of PD beyond age and gender alone (area under ROC curve, c =0.882). Furthermore, we observed a close inverse correlation between α-syn levels in CSF and assigned Hoehn and Yahr score in this cohort of 71 living subjects (p <0.0001), even after adjusting for age. These findings identify in the quantification of α-syn from CSF a potential laboratory marker to aid the clinical diagnosis of PD. [Copyright &y& Elsevier]