| 1. |
- Andersson, E., et al.
(författare)
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Cerebral A beta deposition precedes reduced cerebrospinal fluid and serum A beta 42/A beta 40 ratios in the App(NL-F/NL-F) knock-in mouse model of Alzheimer's disease
- 2023
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Ingår i: Alzheimer's Research & Therapy. - : Springer Science and Business Media LLC. - 1758-9193. ; 15:1
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundA beta 42/A beta 40 ratios in cerebrospinal fluid (CSF) and blood are reduced in preclinical Alzheimer's disease (AD), but their temporal and correlative relationship with cerebral A beta pathology at this early disease stage is not well understood. In the present study, we aim to investigate such relationships using App knock-in mouse models of preclinical AD.MethodsCSF, serum, and brain tissue were collected from 3- to 18-month-old App(NL-F/NL-F) knock-in mice (n = 48) and 2-18-month-old App(NL/NL) knock-in mice (n = 35). The concentrations of A beta 42 and A beta 40 in CSF and serum were measured using Single molecule array (Simoa) immunoassays. Cerebral A beta plaque burden was assessed in brain tissue sections by immunohistochemistry and thioflavin S staining. Furthermore, the concentrations of A beta 42 in soluble and insoluble fractions prepared from cortical tissue homogenates were measured using an electrochemiluminescence immunoassay.ResultsIn App(NL-F/NL-F) knock-in mice, A beta 42/A beta 40 ratios in CSF and serum were significantly reduced from 12 and 16 months of age, respectively. The initial reduction of these biomarkers coincided with cerebral A beta pathology, in which a more widespread A beta plaque burden and increased levels of A beta 42 in the brain were observed from approximately 12 months of age. Accordingly, in the whole study population, A beta 42/A beta 40 ratios in CSF and serum showed a negative hyperbolic association with cerebral A beta plaque burden as well as the levels of both soluble and insoluble A beta 42 in the brain. These associations tended to be stronger for the measures in CSF compared with serum. In contrast, no alterations in the investigated fluid biomarkers or apparent cerebral A beta plaque pathology were found in App(NL/NL) knock-in mice during the observation time.ConclusionsOur findings suggest a temporal sequence of events in App(NL-F/NL-F) knock-in mice, in which initial deposition of A beta aggregates in the brain is followed by a decline of the A beta 42/A beta 40 ratio in CSF and serum once the cerebral A beta pathology becomes significant. Our results also indicate that the investigated biomarkers were somewhat more strongly associated with measures of cerebral A beta pathology when assessed in CSF compared with serum.
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| 2. |
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| 3. |
- Ashton, Nicholas J., et al.
(författare)
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The validation status of blood biomarkers of amyloid and phospho-tau assessed with the 5-phase development framework for AD biomarkers
- 2021
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Ingår i: European Journal of Nuclear Medicine and Molecular Imaging. - : Springer Science and Business Media LLC. - 1619-7070 .- 1619-7089. ; 48
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Tidskriftsartikel (refereegranskat)abstract
- Purpose The development of blood biomarkers that reflect Alzheimer's disease (AD) pathophysiology (phosphorylated tau and amyloid-beta) has offered potential as scalable tests for dementia differential diagnosis and early detection. In 2019, the Geneva AD Biomarker Roadmap Initiative included blood biomarkers in the systematic validation of AD biomarkers. Methods A panel of experts convened in November 2019 at a two-day workshop in Geneva. The level of maturity (fully achieved, partly achieved, preliminary evidence, not achieved, unsuccessful) of blood biomarkers was assessed based on the Biomarker Roadmap methodology and discussed fully during the workshop which also evaluated cerebrospinal fluid (CSF) and positron emission tomography (PET) biomarkers. Results Plasma p-tau has shown analytical validity (phase 2 primary aim 1) and first evidence of clinical validity (phase 3 primary aim 1), whereas the maturity level for A beta remains to be partially achieved. Full and partial achievement has been assigned to p-tau and A beta, respectively, in their associations to ante-mortem measures (phase 2 secondary aim 2). However, only preliminary evidence exists for the influence of covariates, assay comparison and cut-off criteria. Conclusions Despite the relative infancy of blood biomarkers, in comparison to CSF biomarkers, much has already been achieved for phases 1 through 3 - with p-tau having greater success in detecting AD and predicting disease progression. However, sufficient data about the effect of covariates on the biomarker measurement is lacking. No phase 4 (real-world performance) or phase 5 (assessment of impact/cost) aim has been tested, thus not achieved.
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| 4. |
- Blennow, Kaj, 1958, et al.
(författare)
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Evolution of Abeta42 and Abeta40 Levels and Abeta42/Abeta40 Ratio in Plasma during Progression of Alzheimer's Disease: A Multicenter Assessment.
- 2009
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Ingår i: The journal of nutrition, health & aging. - 1279-7707. ; 13:3, s. 205-8
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To better understand the seemingly contradictory plasma beta-amyloid (Abeta) results in Alzheimer's disease (AD) patients by using a newly developed plasma Abeta assay, the INNO-BIA plasma Abeta forms, in a multicenter study. Methods: A combined retrospective analysis of plasma Abeta isoforms on mild cognitive impairment (MCI) from three large cross-sectional studies involving 643 samples from the participating German and Swedish centers. Results: Detection modules based on two different amino (N)-terminal specific Abeta monoclonal antibodies demonstrated that Abeta in plasma could be reliable quantified using a sandwich immunoassay technology with high precision, even for low Abeta42 plasma concentrations. Abeta40 and Abeta42 concentrations varied consistently with the ApoE genotype, while the Abeta42/Abeta40 ratio did not. Irrespective of the decrease of the Abeta42/Abeta40 ratio with age and MMSE, this parameter was strongly associated with AD, as defined in this study by elevated hyperphosphorylated (P-tau181P) levels in cerebrospinal fluid (CSF). Conclusion: A highly robust assay for repeatedly measuring Abeta forms in plasma such as INNO-BIA plasma Abeta forms might be a useful tool in a future risk assessment of AD.
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| 5. |
- Cicognola, C., et al.
(författare)
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Associations of CSF PDGFR & beta; With Aging, Blood-Brain Barrier Damage, Neuroinflammation, and Alzheimer Disease Pathologic Changes
- 2023
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Ingår i: NEUROLOGY. - 0028-3878. ; 101:1, s. E30-E39
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Tidskriftsartikel (refereegranskat)abstract
- Background and ObjectivesInjured pericytes in the neurovascular unit release platelet-derived growth factor & beta; (PDGFR & beta;) into the CSF. However, it is not clear how pericyte injury contributes to Alzheimer disease (AD)-related changes and blood-brain barrier (BBB) damage. We aimed to test whether CSF PDGFR & beta; was associated with different AD-associated and age-associated pathologic changes leading to dementia.MethodsPDGFR & beta; was measured in the CSF of 771 participants with cognitively unimpaired (CU, n = 408), mild cognitive impairment (MCI, n = 175), and dementia (n = 188) from the Swedish BioFINDER-2 cohort. We then checked association with & beta;-amyloid (A & beta;)-PET and tau-PET standardized uptake value ratio, APOE & epsilon;4 genotype and MRI measurements of cortical thickness, white matter lesions (WMLs), and cerebral blood flow. We also analyzed the role of CSF PDGFR & beta; in the relationship between aging, BBB dysfunction (measured by CSF/plasma albumin ratio, QAlb), and neuroinflammation (i.e., CSF levels of YKL-40 and glial fibrillary acidic protein [GFAP], preferentially expressed in reactive astrocytes).ResultsThe cohort had a mean age of 67 years (CU = 62.8, MCI = 69.9, dementia = 70.4), and 50.1% were male (CU = 46.6%, MCI = 53.7%, dementia = 54.3%). Higher CSF PDGFR & beta; concentrations were related to higher age (b = 19.1, & beta; = 0.5, 95% CI 16-22.2, p < 0.001), increased CSF neuroinflammatory markers of glial activation YKL-40 (b = 3.4, & beta; = 0.5, 95% CI 2.8-3.9, p < 0.001), GFAP (b = 27.4, & beta; = 0.4, 95% CI 20.9-33.9, p < 0.001), and worse BBB integrity measured by QAlb (b = 37.4, & beta; = 0.2, 95% CI 24.9-49.9, p < 0.001). Age was also associated with worse BBB integrity, and this was partly mediated by PDGFR & beta; and neuroinflammatory markers (16%-33% of total effect). However, PDGFR & beta; showed no associations with APOE & epsilon;4 genotype, PET imaging of A & beta; and tau pathology, or MRI measures of brain atrophy and WMLs (p > 0.05).DiscussionIn summary, pericyte damage, reflected by CSF PDGFR & beta;, may be involved in age-related BBB disruption together with neuroinflammation, but is not related to Alzheimer-related pathologic changes.
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| 6. |
- Frankel, R., et al.
(författare)
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Autocatalytic amplification of Alzheimer-associated A beta 42 peptide aggregation in human cerebrospinal fluid
- 2019
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 2
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Tidskriftsartikel (refereegranskat)abstract
- Alzheimer's disease is linked to amyloid beta (A beta) peptide aggregation in the brain, and a detailed understanding of the molecular mechanism of A beta 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 A beta 42 in human CSF through kinetic experiments at several A beta 42 monomer concentrations (0.8-10 mu M). The data were subjected to global kinetic analysis and found consistent with an aggregation mechanism involving secondary nucleation of monomers on the fibril surface. A mechanism only including primary nucleation was ruled out. We find that the aggregation process is composed of the same microscopic steps in CSF as in pure buffer, but the rate constant of secondary nucleation is decreased. Most importantly, the autocatalytic amplification of aggregate number through catalysis on the fibril surface is prevalent also in CSF.
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| 7. |
- Janelidze, S., et al.
(författare)
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Head-to-Head Comparison of 8 Plasma Amyloid-beta 42/40 Assays in Alzheimer Disease
- 2021
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Ingår i: Jama Neurology. - : American Medical Association (AMA). - 2168-6149. ; 78:11, s. 1375-1382
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Tidskriftsartikel (refereegranskat)abstract
- IMPORTANCE Blood-based tests for brain amyloid-beta (A beta) pathology are needed for widespread implementation of Alzheimer disease (AD) biomarkers in clinical care and to facilitate patient screening and monitoring of treatment responses in clinical trials. OBJECTIVE To compare the performance of plasma A beta 42/40 measured using 8 different A beta assays when detecting abnormal brain A beta status in patients with early AD. DESIGN, SETTING, AND PARTICIPANTS This study included 182 cognitively unimpaired participants and 104 patients with mild cognitive impairment from the BioFINDER cohort who were enrolled at 3 different hospitals in Sweden and underwent A beta positron emission tomography (PET) imaging and cerebrospinal fluid (CSF) and plasma collection from 2010 to 2014. Plasma A beta 42/40 was measured using an immunoprecipitation-coupled mass spectrometry developed at Washington University (IP-MS-WashU), antibody-free liquid chromatography MS developed by Araclon (LC-MS-Arc), and immunoassays from Roche Diagnostics (IA-Elc); Euroimmun (IA-EI); and Amsterdam University Medical Center, ADx Neurosciences, and Quanterix (IA-N4PE). Plasma A beta 42/40 was also measured using an IP-MS-based method from Shimadzu in 200 participants (IP-MS-Shim) and an IP-MS-based method from the University of Gothenburg (IP-MS-UGOT) and another immunoassay from Quanterix (IA-Quan) among 227 participants. For validation, 122 participants (51 cognitively normal, 51 with mild cognitive impairment, and 20 with AD dementia) were included from the Alzheimer Disease Neuroimaging Initiative who underwent A beta-PET and plasma A beta assessments using IP-MS-WashU, IP-MS-Shim, IP-MS-UGOT, IA-Elc, IA-N4PE, and IA-Quan assays. MAIN OUTCOMES AND MEASURES Discriminative accuracy of plasma A beta 42/40 quantified using 8 different assays for abnormal CSF A beta 42/40 and A beta-PET status. RESULTS A total of 408 participants were included in this study. In the BioFINDER cohort, the mean (SD) age was 71.6 (5.6) years and 49.3% of the cohort were women. When identifying participants with abnormal CSF A beta 42/40 in the whole cohort, plasma IP-MS-WashU A beta 42/40 showed significantly higher accuracy (area under the receiver operating characteristic curve [AUC], 0.86; 95% CI, 0.81-0.90) than LC-MS-Arc A beta 42/40, IA-Elc A beta 42/40, IA-EI A beta 42/40, and IA-N4PE A beta 42/40 (AUC range, 0.69-0.78; P < .05). Plasma IP-MS-WashU A beta 42/40 performed significantly better than IP-MS-UGOT A beta 42/40 and IA-Quan A beta 42/40 (AUC, 0.84 vs 0.68 and 0.64, respectively; P < .001), while there was no difference in the AUCs between IP-MS-WashU A beta 42/40 and IP-MS-Shim A beta 42/40 (0.87 vs 0.83; P = .16) in the 2 subcohorts where these biomarkers were available. The results were similar when using A beta-PET as outcome. Plasma IPMS-WashU A beta 42/40 and IPMS-Shim A beta 42/40 showed highest coefficients for correlations with CSF A beta 42/40 (r range, 0.56-0.65). The BioFINDER results were replicated in the Alzheimer Disease Neuroimaging Initiative cohort (mean [SD] age, 72.4 [5.4] years; 43.4% women), where the IP-MS-WashU assay performed significantly better than the IP-MS-UGOT, IA-Elc, IA-N4PE, and IA-Quan assays but not the IP-MS-Shim assay. CONCLUSIONS AND RELEVANCE The results from 2 independent cohorts indicate that certain MS-based methods performed better than most of the immunoassays for plasma A beta 42/40 when detecting brain A beta pathology.
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| 8. |
- Lautner, Ronald, et al.
(författare)
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Preclinical effects of APOE epsilon 4 on cerebrospinal fluid A beta 42 concentrations
- 2017
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Ingår i: Alzheimers Research & Therapy. - : Springer Science and Business Media LLC. - 1758-9193. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Background: From earlier studies it is known that the APOE epsilon 2/epsilon 3/epsilon 4 polymorphism modulates the concentrations of cerebrospinal fluid (CSF) beta-amyloid(1-42) (A beta 42) in patients with cognitive decline due to Alzheimer's disease (AD), as well as in cognitively healthy controls. Here, in a large cohort consisting solely of cognitively healthy individuals, we aimed to evaluate how the effect of APOE on CSF A beta 42 varies by age, to understand the association between APOE and the onset of preclinical AD. Methods: APOE genotype and CSF A beta 42 concentration were determined in a cohort comprising 716 cognitively healthy individuals aged 17-99 from nine different clinical research centers. Results: CSF concentrations of A beta 42 were lower in APOE epsilon 4 carriers than in noncarriers in a gene dose-dependent manner. The effect of APOE epsilon 4 on CSF A beta 42 was age dependent. The age at which CSF A beta 42 concentrations started to decrease was estimated at 50 years in APOE epsilon 4-negative individuals and 43 years in heterozygous APOE epsilon 4 carriers. Homozygous APOE epsilon 4 carriers showed a steady decline in CSF A beta 42 concentrations with increasing age throughout the examined age span. Conclusions: People possessing the APOE epsilon 4 allele start to show a decrease in CSF A beta 42 concentration almost a decade before APOE epsilon 4 noncarriers already in early middle age. Homozygous APOE epsilon 4 carriers might deposit A beta 42 throughout the examined age span. These results suggest that there is an APOE epsilon 4-dependent period of early alterations in amyloid homeostasis, when amyloid slowly accumulates, that several years later, together with other downstream pathological events such as tau pathology, translates into cognitive decline.
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| 9. |
- Leuzy, A., et al.
(författare)
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2020 update on the clinical validity of cerebrospinal fluid amyloid, tau, and phospho-tau as biomarkers for Alzheimer's disease in the context of a structured 5-phase development framework
- 2021
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Ingår i: European Journal of Nuclear Medicine and Molecular Imaging. - : Springer Science and Business Media LLC. - 1619-7070 .- 1619-7089. ; 48
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Tidskriftsartikel (refereegranskat)abstract
- Purpose In the last decade, the research community has focused on defining reliable biomarkers for the early detection of Alzheimer's disease (AD) pathology. In 2017, the Geneva AD Biomarker Roadmap Initiative adapted a framework for the systematic validation of oncological biomarkers to cerebrospinal fluid (CSF) AD biomarkers-encompassing the 42 amino-acid isoform of amyloid-beta (A beta 42), phosphorylated-tau (P-tau), and Total-tau (T-tau)-with the aim to accelerate their development and clinical implementation. The aim of this work is to update the current validation status of CSF AD biomarkers based on the Biomarker Roadmap methodology. Methods A panel of experts in AD biomarkers convened in November 2019 at a 2-day workshop in Geneva. The level of maturity (fully achieved, partly achieved, preliminary evidence, not achieved, unsuccessful) of CSF AD biomarkers was assessed based on the Biomarker Roadmap methodology before the meeting and presented and discussed during the workshop. Results By comparison to the previous 2017 Geneva Roadmap meeting, the primary advances in CSF AD biomarkers have been in the area of a unified protocol for CSF sampling, handling and storage, the introduction of certified reference methods and materials for A beta 42, and the introduction of fully automated assays. Additional advances have occurred in the form of defining thresholds for biomarker positivity and assessing the impact of covariates on their discriminatory ability. Conclusions Though much has been achieved for phases one through three, much work remains in phases four (real world performance) and five (assessment of impact/cost). To a large degree, this will depend on the availability of disease-modifying treatments for AD, given these will make accurate and generally available diagnostic tools key to initiate therapy.
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| 10. |
- Leuzy, A., et al.
(författare)
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Robustness of CSF A beta 42/40 and A beta 42/P-tau181 measured using fully automated immunoassays to detect AD-related outcomes
- 2023
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Ingår i: Alzheimers & Dementia. - : Wiley. - 1552-5260 .- 1552-5279. ; 19:7, s. 2994-3004
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Tidskriftsartikel (refereegranskat)abstract
- IntroductionThis study investigated the comparability of cerebrospinal fluid (CSF) cutoffs for Elecsys immunoassays for amyloid beta (A beta)42/A beta 40 or A beta 42/phosphorylated tau (p-tau)181 and the effects of measurement variability when predicting Alzheimer's disease (AD)-related outcomes (i.e., A beta-positron emission tomography [PET] visual read and AD neuropathology). MethodsWe studied 750 participants (BioFINDER study, Alzheimer's Disease Neuroimaging Initiative [ADNI], and University of California San Francisco [UCSF]). Youden's index was used to identify cutoffs and to calculate accuracy (A beta-PET visual read as outcome). Using longitudinal variability in A beta-negative controls, we identified a gray zone around cut-points where the risk of an inconsistent predicted outcome was >5%. ResultsFor A beta 42/A beta 40, cutoffs across cohorts were <0.059 (BioFINDER), <0.057 (ADNI), and <0.058 (UCSF). For A beta 42/p-tau181, cutoffs were <41.90 (BioFINDER), <39.20 (ADNI), and <46.02 (UCSF). Accuracy was approximate to 90% for both A beta 42/A beta 40 and A beta 42/p-tau181 using these cutoffs. Using A beta-PET as an outcome, 8.7% of participants fell within a gray zone interval for A beta 42/A beta 40, compared to 4.5% for A beta 42/p-tau181. Similar findings were observed using a measure of overall AD neuropathologic change (7.7% vs. 3.3%). In a subset with CSF and plasma A beta 42/40, the number of individuals within the gray zone was approximate to 1.5 to 3 times greater when using plasma A beta 42/40. DiscussionCSF A beta 42/p-tau181 was more robust to the effects of measurement variability, suggesting that it may be the preferred Elecsys-based measure in clinical practice and trials.
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