| 1. |
- Brinkmalm, Gunnar, et al.
(författare)
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An online nano-LC-ESI-FTICR-MS method for comprehensive characterization of endogenous fragments from amyloid β and amyloid precursor protein in human and cat cerebrospinal fluid.
- 2012
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Ingår i: Journal of mass spectrometry : JMS. - : Wiley. - 1096-9888 .- 1076-5174. ; 47:5, s. 591-603
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Tidskriftsartikel (refereegranskat)abstract
- Amyloid precursor protein (APP) is the precursor protein to amyloid β (Aβ), the main constituent of senile plaques in Alzheimer's disease (AD). Endogenous Aβ peptides reflect the APP processing, and greater knowledge of different APP degradation pathways is important to understand the mechanism underlying AD pathology. When one analyzes longer Aβ peptides by low-energy collision-induced dissociation tandem mass spectrometry (MS/MS), mainly long b-fragments are observed, limiting the possibility to determine variations such as amino acid variants or post-translational modifications (PTMs) within the N-terminal half of the peptide. However, by using electron capture dissociation (ECD), we obtained a more comprehensive sequence coverage for several APP/Aβ peptide species, thus enabling a deeper characterization of possible variants and PTMs. Abnormal APP/Aβ processing has also been described in the lysosomal storage disease Niemann-Pick type C and the major large animal used for studying this disease is cat. By ECD MS/MS, a substitution of Asp7 → Glu in cat Aβ was identified. Further, sialylated core 1 like O-glycans at Tyr10, recently discovered in human Aβ (a previously unknown glycosylation type), were identified also in cat cerebrospinal fluid (CSF). It is therefore likely that this unusual type of glycosylation is common for (at least) species belonging to the magnorder Boreoeutheria. We here describe a detailed characterization of endogenous APP/Aβ peptide species in CSF by using an online top-down MS-based method.
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| 2. |
- Brinkmalm, Gunnar, et al.
(författare)
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Soluble amyloid precursor protein α and β in CSF in Alzheimer's disease.
- 2013
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Ingår i: Brain research. - : Elsevier BV. - 1872-6240 .- 0006-8993. ; 1513, s. 117-26
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Tidskriftsartikel (refereegranskat)abstract
- Cerebral accumulation of amyloid β (Aβ) is a pathological hallmark of Alzheimer's disease (AD). Proteolytic processing of amyloid precursor protein (APP) by α- or β-secretase results in two soluble metabolites, sAPPα and sAPPβ, respectively. However, previous data have shown that both α- and β-secretase have multiple cleavage sites. The aim of this study was to characterize the C-termini of sAPPα and sAPPβ in cerebrospinal fluid (CSF) by mass spectrometry (MS) and to evaluate whether different combinations of these fragments better separate between AD patients and controls by comparing two different sAPP immunoassays. Methods: Using immunoprecipitation and high resolution MS, the APP species present in CSF were investigated. CSF levels of sAPPα and sAPPβ from patients with AD (n=43) and from non-demented controls (n=44) were measured using AlphaLISA and MSD immunoassays that employ different antibodies for C-terminal recognition of sAPPα. Results: Four different C-terminal forms of sAPP were identified, sAPPβ-M671, sAPPβ-Y681, sAPPα-Q686, and sAPPα-K687 (APP770 numbering). Neither immunoassay for the sAPP species could separate the two patient groups. The correlation (R(2)) between the two immunoassays was 0.41 for sAPPα and 0.45 for sAPPβ. Conclusion: Using high resolution MS, we show here for the first time that sAPPα in CSF ends at Q686 and K687. The findings also support the conclusion from several previous studies that sAPPα and sAPPβ levels are unaltered in AD.
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| 3. |
- Brinkmalm-Westman, Ann, 1966, et al.
(författare)
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SNAP-25 is a promising novel cerebrospinal fluid biomarker for synapse degeneration in Alzheimer's disease
- 2014
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Ingår i: Molecular Neurodegeneration. - : Springer Science and Business Media LLC. - 1750-1326. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Background: Synaptic degeneration is an early pathogenic event in Alzheimer's disease, associated with cognitive impairment and disease progression. Cerebrospinal fluid biomarkers reflecting synaptic integrity would be highly valuable tools to monitor synaptic degeneration directly in patients. We previously showed that synaptic proteins such as synaptotagmin and synaptosomal-associated protein 25 (SNAP-25) could be detected in pooled samples of cerebrospinal fluid, however these assays were not sensitive enough for individual samples. Results: We report a new strategy to study synaptic pathology by using affinity purification and mass spectrometry to measure the levels of the presynaptic protein SNAP-25 in cerebrospinal fluid. By applying this novel affinity mass spectrometry strategy on three separate cohorts of patients, the value of SNAP-25 as a cerebrospinal fluid biomarker for synaptic integrity in Alzheimer's disease was assessed for the first time. We found significantly higher levels of cerebrospinal fluid SNAP-25 fragments in Alzheimer's disease, even in the very early stages, in three separate cohorts. Cerebrospinal fluid SNAP-25 differentiated Alzheimer's disease from controls with area under the curve of 0.901 (P < 0.0001). Conclusions: We developed a sensitive method to analyze SNAP-25 levels in individual CSF samples that to our knowledge was not possible previously. Our results support the notion that synaptic biomarkers may be important tools for early diagnosis, assessment of disease progression, and to monitor drug effects in treatment trials.
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| 4. |
- Brinkmalm-Westman, Ann, 1966, et al.
(författare)
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Targeting synaptic pathology with a novel affinity mass spectrometry approach.
- 2014
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Ingår i: Molecular & cellular proteomics : MCP. - 1535-9484. ; 13:10, s. 2584-92
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Tidskriftsartikel (refereegranskat)abstract
- We report a novel strategy for studying synaptic pathology by concurrently measuring levels of four SNARE complex proteins from individual brain tissue samples. This method combines affinity purification and mass spectrometry and can be applied directly for studies of SNARE complex proteins in multiple species or modified to target other key elements in neuronal function. We use the technique to demonstrate altered levels of presynaptic proteins in Alzheimer disease patients and prion-infected mice.
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| 5. |
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| 6. |
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| 7. |
- Nutu, Magdalena, 1967, et al.
(författare)
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Evaluation of the Cerebrospinal Fluid Amyloid-β1-42/Amyloid-β1-40 Ratio Measured by Alpha-LISA to Distinguish Alzheimer's Disease from Other Dementia Disorders.
- 2013
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Ingår i: Dementia and geriatric cognitive disorders. - : S. Karger AG. - 1421-9824 .- 1420-8008. ; 36:1-2, s. 99-110
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Tidskriftsartikel (refereegranskat)abstract
- Background: The well-established core biomarkers used to identify Alzheimer's disease (AD) overlap with other dementia disorders such as dementia with Lewy bodies (DLB) and Parkinson's disease with dementia (PDD). This study aimed to evaluate whether the cerebrospinal fluid (CSF) amyloid-β (Aβ)1-42/Aβ1-40 ratio, measured by a novel method, could improve the differential diagnosis of AD, DLB and PDD. Method: CSF levels of Aβ1-40 and Aβ1-42 in patients with PDD, DLB, AD, Parkinson's disease and controls were analyzed using an amplified luminescent proximity homogenous immunoassay along with conventional immunoassays. Results: The CSF Aβ1-42/Aβ1-40 ratio increased discrimination of AD from PDD and DLB compared with either of the two Aβ biomarkers individually. Conclusion: The use of the Aβ1-42/Aβ1-40 ratio could improve the differentiation of AD from PDD and DLB. © 2013 S. Karger AG, Basel.
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| 8. |
- Portelius, Erik, 1977, et al.
(författare)
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Identification of novel N-terminal fragments of amyloid precursor protein in cerebrospinal fluid.
- 2010
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Ingår i: Experimental neurology. - : Elsevier BV. - 1090-2430 .- 0014-4886. ; 223:2, s. 351-358
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Tidskriftsartikel (refereegranskat)abstract
- Alzheimer's disease (AD) is a progressive neurodegenerative disorder of the central nervous system. Two pathological hallmarks in the brain of AD patients are neurofibrillary tangles and senile plaques. The plaques consist mainly of beta-amyloid (Abeta) peptides that are produced from the amyloid precursor protein (APP), by sequential cleavage by beta- and gamma-secretase. Most previous studies have been focused on the C-terminal fragments of APP, where the Abeta sequence is localized. The purpose of this study was to search for N-terminal fragments of APP in cerebrospinal fluid (CSF) using mass spectrometry (MS). By using immunoprecipitation (IP) combined with matrix-assisted laser desorption/ionization time-of-flight MS as well as nanoflow liquid chromatography coupled to high resolution tandem MS we were able to detect and identify six novel N-terminal APP fragments [APP((18-119)), APP((18-121)), APP((18-122)), APP((18-123)), APP((18-124)) and APP((18-126))], having molecular masses of approximately 12 kDa. The presence of these APP derivatives in CSF was also verified by Western blot analysis. Two pilot studies using either IP-MS or Western blot analysis indicated slightly elevated levels of N-terminal APP fragments in CSF from AD patients compared with controls, which are in need of replications in independent and larger patient materials.
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| 9. |
- Trupp, Miles, et al.
(författare)
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Metabolite and peptide levels in plasma and CSF differentiating healthy controls from patients with newly diagnosed Parkinson's disease
- 2014
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Ingår i: Journal of Parkinson's Disease. - : Taylor & Francis. - 1877-7171 .- 1877-718X. ; 4:3, s. 549-560
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Tidskriftsartikel (refereegranskat)abstract
- Background: Parkinson's disease (PD) is a progressive, multi-focal neurodegenerative disease for which there is no effective disease modifying treatment. A critical requirement for designing successful clinical trials is the development of robust and reproducible biomarkers identifying PD in preclinical stages. Objective: To investigate the potential for a cluster of biomarkers visualized with multiple analytical platforms to provide a clinically useful tool. Methods: Gas Chromatography-Mass Spectrometry (GC-TOFMS) based metabolomics and immunoassay-based protein/peptide analyses on samples from patients with PD diagnosed in Northern Sweden. Low molecular weight compounds from both plasma and cerebrospinal fluid (CSF) from 20 healthy subjects (controls) and 20 PD patients at the time of diagnosis (baseline) were analyzed. Results: In plasma, we found a significant increase in several amino acids and a decrease in C16-C18 saturated and unsaturated fatty acids in patients as compared to control subjects. We also observed an increase in plasma levels of pyroglutamate and 2-oxoisocaproate (ketoleucine) that may be indicative of increased metabolic stress in patients. In CSF, there was a generally lower level of metabolites in PD as compared to controls, with a specific decrease in 3-hydroxyisovaleric acid, tryptophan and creatinine. Multivariate analysis and modeling of metabolites indicates that while the PD samples can be separated from control samples, the list of detected compounds will need to be expanded in order to define a robust predictive model. CSF biomarker immunoassays of candidate peptide/protein biomarkers revealed a significant decrease in the levels of A beta-38 and A beta-42, and an increase in soluble APP alpha in CSF of patients. Furthermore, these peptides showed significant correlations to each other, and positive correlations to the CSF levels of several 5- and 6-carbon sugars. However, combining these metabolites and proteins/peptides into a single model did not significantly improve the statistical analysis. Conclusions: Together, this metabolomics study has detected significant alterations in plasma and CSF levels of a cluster of amino acids, fatty acids and sugars based on clinical diagnosis and levels of known protein and peptide biomarkers.
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| 10. |
- Öhrfelt Olsson, Annika, 1973, et al.
(författare)
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Identification of Novel α-Synuclein Isoforms in Human Brain Tissue by using an Online NanoLC-ESI-FTICR-MS Method.
- 2011
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Ingår i: Neurochemical research. - : Springer Science and Business Media LLC. - 1573-6903 .- 0364-3190. ; 36:11
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Tidskriftsartikel (refereegranskat)abstract
- Parkinson's disease (PD) and Dementia with Lewy bodies (DLB) are neurodegenerative diseases that are characterized by intra-neuronal inclusions of Lewy bodies in distinct brain regions. These inclusions consist mainly of aggregated α-synuclein (α-syn) protein. The present study used immunoprecipitation combined with nanoflow liquid chromatography (LC) coupled to high resolution electrospray ionization Fourier transform ion cyclotron resonance tandem mass spectrometry (ESI-FTICR-MS/MS) to determine known and novel isoforms of α-syn in brain tissue homogenates. N-terminally acetylated full-length α-syn (Ac-α-syn(1-140)) and two N-terminally acetylated C-terminally truncated forms of α-syn (Ac-α-syn(1-139) and Ac-α-syn(1-103)) were found. The different forms of α-syn were further studied by Western blotting in brain tissue homogenates from the temporal cortex Brodmann area 36 (BA36) and the dorsolateral prefrontal cortex BA9 derived from controls, patients with DLB and PD with dementia (PDD). Quantification of α-syn in each brain tissue fraction was performed using a novel enzyme-linked immunosorbent assay (ELISA).
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