Autocatalytic amplification of Alzheimer-associated A?42 peptide aggregation in human cerebrospinal fluid.
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ABSTRACT:
SUBMITTER: Frankel R
PROVIDER: S-EPMC6783456 | biostudies-literature | 2019
REPOSITORIES: biostudies-literature
Publications
Autocatalytic amplification of Alzheimer-associated Aβ42 peptide aggregation in human cerebrospinal fluid.
Frankel Rebecca R Törnquist Mattias M Meisl Georg G Hansson Oskar O Andreasson Ulf U Zetterberg Henrik H Blennow Kaj K Frohm Birgitta B Cedervall Tommy T Knowles Tuomas P J TPJ Leiding Thom T Linse Sara S
Communications biology 20191008
Alzheimer's disease is linked to amyloid β (Aβ) peptide aggregation in the brain, and a detailed understanding of the molecular mechanism of Aβ aggregation may lead to improved diagnostics and therapeutics. While previous studies have been performed in pure buffer, we approach the mechanism in vivo using cerebrospinal fluid (CSF). We investigated the aggregation mechanism of Aβ42 in human CSF through kinetic experiments at several Aβ42 monomer concentrations (0.8-10 µM). The data were subjected ...[more]
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Project description:BACKGROUND:Over the past 2 decades, clinical studies have provided evidence that cerebrospinal fluid (CSF) amyloid ?(1-42) (A?(1-42)), total ? (t-?), and ? phosphorylated at Thr181 (p-?(181)) are reliable biochemical markers of Alzheimer disease (AD) neuropathology. CONTENT:In this review, we summarize the clinical performance and describe the major challenges for the analytical performance of the most widely used immunoassay platforms [based on ELISA or microbead-based multianalyte profiling (xMAP) technology] for the measurement of CSF AD biomarkers (A?(1-42), t-?, and p-?(181)). With foundational immunoassay data providing the diagnostic and prognostic values of CSF AD biomarkers, the newly revised criteria for the diagnosis of AD include CSF AD biomarkers for use in research settings. In addition, it has been suggested that the selection of AD patients at the predementia stage by use of CSF AD biomarkers can improve the statistical power of clinical trial design. Owing to the lack of a replenishable and commutable human CSF-based standardized reference material (SRM) and significant differences across different immunoassay platforms, the diagnostic-prognostic cutpoints of CSF AD biomarker concentrations are not universal at this time. These challenges can be effectively met in the future, however, through collaborative ongoing standardization efforts to minimize the sources of analytical variability and to develop reference methods and SRMs. SUMMARY:Measurements of CSF A?(1-42), t-?, and p-?(181) with analytically qualified immunoassays reliably reflect the neuropathologic hallmarks of AD in patients at the early predementia stage of the disease and even in presymptomatic patients. Thus these CSF biomarker tests are useful for early diagnosis of AD, prediction of disease progression, and efficient design of drug intervention clinical trials.
| S-EPMC4159709 | biostudies-literature
Project description:BackgroundAggregation of α-synuclein (α-syn) is a prominent feature of Parkinson's disease (PD) and other synucleinopathies. Currently, α-syn seed amplification assays (SAAs) using cerebrospinal fluid (CSF) represent the most promising diagnostic tools for synucleinopathies. However, CSF itself contains several compounds that can modulate the aggregation of α-syn in a patient-dependent manner, potentially undermining unoptimized α-syn SAAs and preventing seed quantification.MethodsIn this study, we characterized the inhibitory effect of CSF milieu on detection of α-syn aggregates by means of CSF fractionation, mass spectrometry, immunoassays, transmission electron microscopy, solution nuclear magnetic resonance spectroscopy, a highly accurate and standardized diagnostic SAA, and different in vitro aggregation conditions to evaluate spontaneous aggregation of α-syn.ResultsWe found the high-molecular weight fraction of CSF (> 100,000 Da) to be highly inhibitory on α-syn aggregation and identified lipoproteins to be the main drivers of this effect. Direct interaction between lipoproteins and monomeric α-syn was not detected by solution nuclear magnetic resonance spectroscopy, on the other hand we observed lipoprotein-α-syn complexes by transmission electron microscopy. These observations are compatible with hypothesizing an interaction between lipoproteins and oligomeric/proto-fibrillary α-syn intermediates. We observed significantly slower amplification of α-syn seeds in PD CSF when lipoproteins were added to the reaction mix of diagnostic SAA. Additionally, we observed a decreased inhibition capacity of CSF on α-syn aggregation after immunodepleting ApoA1 and ApoE. Finally, we observed that CSF ApoA1 and ApoE levels significantly correlated with SAA kinetic parameters in n = 31 SAA-negative control CSF samples spiked with preformed α-syn aggregates.ConclusionsOur results describe a novel interaction between lipoproteins and α-syn aggregates that inhibits the formation of α-syn fibrils and could have relevant implications. Indeed, the donor-specific inhibition of CSF on α-syn aggregation explains the lack of quantitative results from analysis of SAA-derived kinetic parameters to date. Furthermore, our data show that lipoproteins are the main inhibitory components of CSF, suggesting that lipoprotein concentration measurements could be incorporated into data analysis models to eliminate the confounding effects of CSF milieu on α-syn quantification efforts.
| S-EPMC10068178 | biostudies-literature
Project description:BackgroundAltered proteome profiles have been reported in both postmortem brain tissues and body fluids of subjects with Alzheimer disease (AD), but their broad relationships with AD pathology, amyloid pathology, and tau-related neurodegeneration have not yet been fully explored. Using a robust automated MS-based proteomic biomarker discovery workflow, we measured cerebrospinal fluid (CSF) proteomes to explore their association with well-established markers of core AD pathology.MethodsCross-sectional analysis was performed on CSF collected from 120 older community-dwelling adults with normal (n?=?48) or impaired cognition (n?=?72). LC-MS quantified hundreds of proteins in the CSF. CSF concentrations of ?-amyloid 1-42 (A?1-42), tau, and tau phosphorylated at threonine 181 (P-tau181) were determined with immunoassays. First, we explored proteins relevant to biomarker-defined AD. Then, correlation analysis of CSF proteins with CSF markers of amyloid pathology, neuronal injury, and tau hyperphosphorylation (i.e., A?1-42, tau, P-tau181) was performed using Pearson's correlation coefficient and Bonferroni correction for multiple comparisons.ResultsWe quantified 790 proteins in CSF samples with MS. Four CSF proteins showed an association with CSF A?1-42 levels (p value ??0.05 with correlation coefficient (R)???0.38). We identified 50 additional CSF proteins associated with CSF tau and 46 proteins associated with CSF P-tau181 (p value ??0.05 with R???0.37). The majority of those proteins that showed such associations were brain-enriched proteins. Gene Ontology annotation revealed an enrichment for synaptic proteins and proteins originating from reelin-producing cells and the myelin sheath.ConclusionsWe used an MS-based proteomic workflow to profile the CSF proteome in relation to cerebral AD pathology. We report strong evidence of previously reported CSF proteins and several novel CSF proteins specifically associated with amyloid pathology or neuronal injury and tau hyperphosphorylation.
| S-EPMC6052524 | biostudies-literature
Project description:Low frequency coding variants in TREM2 are associated with increased Alzheimer disease (AD) risk, while loss of functions mutations in the gene lead to an autosomal recessive early-onset dementia, named Nasu-Hakola disease (NHD). TREM2 can be detected as a soluble protein in cerebrospinal fluid (CSF) and plasma, and its CSF levels are elevated in inflammatory CNS diseases. We measured soluble TREM2 (sTREM2) in the CSF of a large AD case-control dataset (n = 180) and 40 TREM2 risk variant carriers to determine whether CSF sTREM2 levels are associated with AD status or mutation status. We also performed genetic studies to identify genetic variants associated with CSF sTREM2 levels. CSF, but not plasma, sTREM2 was highly correlated with CSF total tau and phosphorylated-tau levels (r = 0.35, P < 1×10(-4); r = 0.40, P < 1×10(-4), respectively), but not with CSF A?42. AD cases presented higher CSF sTREM2 levels than controls (P = 0.01). Carriers of NHD-associated TREM2 variants presented significantly lower CSF sTREM2 levels, supporting the hypothesis that these mutations lead to reduced protein production/function (R136Q, D87N, Q33X or T66M; P = 1×10(-3)). In contrast, CSF sTREM2 levels were significantly higher in R47H carriers compared to non-carriers (P = 6×10(-3)), suggesting that this variant does not impact protein expression and increases AD risk through a different pathogenic mechanism than NHD variants. In GWAS analyses for CSF sTREM2 levels the most significant signal was located on the MS4A gene locus (P = 5.45 × 10(-07)) corresponding to one of the SNPs reported to be associated with AD risk in this locus. Furthermore, SNPs involved in pathways related to virus cellular entry and vesicular trafficking were overrepresented, suggesting that CSF sTREM2 levels could be an informative phenotype for AD.
| S-EPMC4867123 | biostudies-literature
Project description:Human cerebrospinal fluid (CSF) contains diverse lipid particles, including lipoproteins that are distinct from their plasma counterparts and contain apolipoprotein (apo) E isoforms, apoJ, and apoAI, and extracellular vesicles, which can be detected by annexin V binding. The aim of this study was to develop a method to quantify CSF particles and evaluate their relationship to aging and neurodegenerative diseases. We used a flow cytometric assay to detect annexin V-, apoE-, apoAI-, apoJ-, and amyloid (A) ?42-positive particles in CSF from 131 research volunteers who were neurologically normal or had mild cognitive impairment (MCI), Alzheimer disease (AD) dementia, or Parkinson disease. APOE ?4/?4 participants had CSF apoE-positive particles that were more frequently larger but at an 88% lower level versus those in APOE ?3/?3 or APOE ?3/?4 patients; this finding was reproduced in conditioned medium from mouse primary glial cell cultures with targeted replacement of apoE. Cerebrospinal fluid apoE-positive and ?-amyloid (A?42)-positive particle concentrations were persistently reduced one-third to one-half in middle and older age subjects; apoAI-positive particle concentration progressively increased approximately 2-fold with age. Both apoAI-positive and annexin V-positive CSF particle levels were reduced one-third to one-half in CSF of MCI and/or AD dementia patients versus age-matched controls. Our approach provides new methods to investigate CNS lipid biology in relation to neurodegeneration and perhaps develop new biomarkers for diagnosis or treatment monitoring.
| S-EPMC4471879 | biostudies-literature
Project description:Plaques containing the aggregated beta-Amyloid (Abeta) peptide in the brain are the main indicators of Alzheimer's disease. Fibrils, the building blocks of plaques, can also be produced in vitro and consist of a regular arrangement of the peptide. The initial steps of fibril formation are not well understood and could involve smaller aggregates (oligomers) of Abeta. Such oligomers have even been implicated as the toxic agents. Here, a method to study oligomers on the time scale of aggregation is suggested. We have labeled the 40 residue Abeta peptide variant containing an N-terminal cysteine (cys-Abeta) with the MTSL [1-oxyl-2,2,5,5-tetramethyl-Delta-pyrroline-3-methyl] methanethiosulfonate spin label (SL-Abeta). Fibril formation in solutions of pure SL-Abeta and of SL-Abeta mixed with Abeta was shown by Congo-red binding and electron microscopy. Continuous-wave 9 GHz electron paramagnetic resonance reveals three fractions of different spin-label mobility: one attributed to monomeric Abeta, one to a multimer (8-15 monomers), and the last one to larger aggregates or fibrils. The approach, in principle, allows detection of oligomers on the time scale of aggregation.
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Project description:Proteolytic fragments of amyloid and post-translational modification of tau species in Cerebrospinal fluid (CSF) as well as cerebral amyloid deposition are important biomarkers for Alzheimer's Disease. We conducted genome-wide association study to identify genetic factors influencing CSF biomarker level, cerebral amyloid deposition, and disease progression. The genome-wide association study was performed via a meta-analysis of two non-overlapping discovery sample sets to identify genetic variants other than APOE ε4 predictive of the CSF biomarker level (Aβ1-42, t-Tau, p-Tau181P, t-Tau:Aβ1-42 ratio, and p-Tau181P:Aβ1-42 ratio) in patients enrolled in the Alzheimer's Disease Neuroimaging Initiative (ADNI) study. Loci passing a genome-wide significance threshold of P < 5 x 10-8 were followed-up for replication in an independent sample set. We also performed joint meta-analysis of both discovery sample sets together with the replication sample set. In the discovery phase, we identified variants in FRA10AC1 associated with CSF Aβ1-42 level passing the genome-wide significance threshold (directly genotyped SNV rs10509663 PFE = 1.1 x 10-9, imputed SNV rs116953792 PFE = 3.5 x 10-10), rs116953792 (Pone-sided = 0.04) achieved replication. This association became stronger in the joint meta-analysis (directly genotyped SNV rs10509663 PFE = 1.7 x 10-9, imputed SNV rs116953792 PFE = 7.6 x 10-11). Additionally, we identified locus 15q21 (imputed SNV rs1503351 PFE = 4.0 x 10-8) associated with CSF Aβ1-42 level. No other variants passed the genome-wide significance threshold for other CSF biomarkers in either the discovery sample sets or joint analysis. Gene set enrichment analyses suggested that targeted genes mediated by miR-33, miR-146, and miR-193 were enriched in various GWAS analyses. This finding is particularly important because CSF biomarkers confer disease susceptibility and may be predictive of the likelihood of disease progression in Alzheimer's Disease.
| S-EPMC4529186 | biostudies-literature
Project description:BACKGROUND:Neurogranin (Ng) is a small 7.6 kDa postsynaptic protein that has been detected at elevated concentrations in cerebrospinal fluid (CSF) of patients with Alzheimer's disease (AD), both as a full-length molecule and as fragments from its C-terminal half. Ng is involved in postsynaptic calcium (Ca) signal transduction and memory formation via binding to calmodulin in a Ca-dependent manner. The mechanism of Ng secretion from neurons to CSF is currently unknown, but enzymatic cleavage of Ng may be of relevance. Therefore, the aim of the study was to identify the enzymes responsible for the cleavage of Ng, yielding the Ng fragment pattern of C-terminal fragments detectable and increased in CSF of AD patients. METHODS:Fluorigenic quenched FRET probes containing sequences of Ng were utilized to identify Ng cleaving activities among enzymes known to have increased activity in AD and in chromatographically fractionated mouse brain extracts. RESULTS:Human Calpain-1 and prolyl endopeptidase were identified as the candidate enzymes involved in the formation of endogenous Ng peptides present in CSF, cleaving mainly in the central region of Ng, and between amino acids 75_76 in the Ng sequence, respectively. The cleavage by Calpain-1 affects the IQ domain of Ng, which may deactivate or change the function of Ng in Ca2+/calmodulin -dependent signaling for synaptic plasticity. While shorter Ng fragments were readily cleaved in vitro by prolyl endopeptidase, the efficiency of cleavage on larger Ng fragments was much lower. CONCLUSIONS:Calpain-1 and prolyl endopeptidase cleave Ng in the IQ domain and near the C-terminus, respectively, yielding specific fragments of Ng in CSF. These fragments may give clues to the roles of increased activities of these enzymes in the pathophysiology of AD, and provide possible targets for pharmacologic intervention.
| S-EPMC6116393 | biostudies-literature
Project description:A possible involvement of the gene IL1RAP (interleukin-1 receptor-associated protein) in the pathogenesis of Alzheimer's disease (AD) has been suggested in GWASs of cerebrospinal fluid (CSF) tau levels and longitudinal change in brain amyloid burden. The aim of this study was to examine previously implicated genetic markers in and near IL1RAP in relation to AD risk, CSF tau and A? biomarkers, as well as cognitive decline, in a case (AD)-control study and an age homogenous population-based cohort. Genotyping of IL1RAP-related single nucleotide polymorphisms (SNPs), selected based on previous GWAS results, was performed. 3446 individuals (1154 AD cases and 2292 controls) were included in the analyses of AD risk, 1400 individuals (cognitively normal?=?747, AD?=?653) in the CSF biomarker analyses, and 861 individuals in the analyses of cognitive decline. We found no relation between IL1RAP-related SNPs and AD risk. However, CSF total-tau and phospho-tau were associated with the SNP rs9877502 (p?=?6?×?10-3 and p?=?5?×?10-4). Further, nominal associations (p?=?0.03-0.05) were found between three other SNPs and CSF biomarker levels, or levels of cognitive performance and decline in a sub-sample from the general population. These results support previous studies suggesting an association of IL1RAP with disease intensity of AD.
| S-EPMC6385252 | biostudies-literature
Project description:Resting-state functional connectivity magnetic resonance imaging has great potential for characterizing pathophysiological changes during the preclinical phase of Alzheimer disease.To assess the relationship between default mode network integrity and cerebrospinal fluid biomarkers of Alzheimer disease pathology in cognitively normal older individuals.Cross-sectional cohort study at The Charles F. and Joanne Knight Alzheimer's Disease Research Center at Washington University in St Louis, St Louis, Missouri, among 207 older adults with normal cognition (Clinical Dementia Rating, 0).Resting-state functional connectivity magnetic resonance imaging measures of default mode network integrity.Decreased cerebrospinal fluid A?42 and increased cerebrospinal fluid phosphorylated tau181 were independently associated with reduced default mode network integrity, with the most prominent decreases in functional connectivity observed between the posterior cingulate and medial temporal regions. Observed reductions in functional connectivity were unattributable to age or structural atrophy in the posterior cingulate and medial temporal areas. Similar resting-state functional connectivity magnetic resonance imaging findings in relation to cerebrospinal fluid biomarkers were obtained using region-of-interest analyses and voxelwise correlation mapping.Both A? and tau pathology affect default mode network integrity before clinical onset of Alzheimer disease.
| S-EPMC3836828 | biostudies-literature