Novel CSF β-synuclein-specific assays signal early synaptic degeneration in Alzheimer’s disease

Abstract Background Beta-synuclein (β-syn), measured at N-terminal epitopes, is an emerging cerebrospinal fluid (CSF) biomarker for synaptic degeneration in Alzheimer's disease (AD). Targeting the mid-region or C-terminus of β-syn may enhance analytical specificity due to the distinct structure...

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Main Authors: Sherif Bayoumy, Julie Goossens, Charlotte De Rocker, Senna Y. Sie, Nolan J. Barrett, Wiesje M. van der Flier, Charlotte E. Teunissen, Eugeen Vanmechelen, Inge M. W. Verberk
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Language:English
Published: BMC 2025-04-01
Series:Alzheimer’s Research & Therapy
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Online Access:https://doi.org/10.1186/s13195-025-01716-8
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author Sherif Bayoumy
Julie Goossens
Charlotte De Rocker
Senna Y. Sie
Nolan J. Barrett
Wiesje M. van der Flier
Charlotte E. Teunissen
Eugeen Vanmechelen
Inge M. W. Verberk
author_facet Sherif Bayoumy
Julie Goossens
Charlotte De Rocker
Senna Y. Sie
Nolan J. Barrett
Wiesje M. van der Flier
Charlotte E. Teunissen
Eugeen Vanmechelen
Inge M. W. Verberk
author_sort Sherif Bayoumy
collection DOAJ
description Abstract Background Beta-synuclein (β-syn), measured at N-terminal epitopes, is an emerging cerebrospinal fluid (CSF) biomarker for synaptic degeneration in Alzheimer's disease (AD). Targeting the mid-region or C-terminus of β-syn may enhance analytical specificity due to the distinct structures of these regions across the synuclein protein family, unlike targeting the N-terminus, which is conserved across the family. This study aimed to confirm that β-syn is a promising CSF biomarker in AD, using novel assays designed to target different regions of β-syn, to investigate whether these regions are differentially affected in AD. Methods We developed two novel CSF β-syn-specific ELISAs targeting mid-region and C-terminus epitopes and assessed their analytical performance. Using these novel assays in combination with the established N-terminus ELISA, we analyzed a proof-of-concept cohort comprising biomarker-confirmed AD (n = 25) and non-AD subjects (n = 25) and a larger clinical cohort (n = 160) from the Amsterdam Dementia Cohort, wich included 41 individuals with subjective cognitive decline (SCD, controls; AD biomarker negative; 64.3 ± 3.3 years, 23 females), 39 with SCD (AD biomarker positive; 65.7 ± 3.1 years, 17 females), 40 with mild cognitive impairment due to AD (MCI-AD; 66.2 ± 2.9 years, 20 females), and 40 with AD dementia (AD-dem; 65.3 ± 3.4 years, 20 females). Results Both the mid-region and C-terminus assays demonstrated reliable analytical performance. All assays consistently detected β-syn in all clinical samples above their limits of detection, with a good average intra-assay coefficient of variation (range of the three assays: 2.7–6.5%CV) in the proof-of-concept cohort and clinical cohort (range of the three assays: 3.9–7.5%CV). CSF β-syn levels, with all the assays, were significantly elevated in all the AD groups compared with the controls in both cohorts. The diagnostic performance of the assays for distinguishing AD patients from controls was comparable (Delong's p > 0.05, AUC 0.71–0.80). Notably, mid-region β-syn significantly differentiated SCD-AD patients from AD-dem patients (p = 0.035) and MCI-AD patients at a trend level. Only mid-region and C-terminal levels correlated with MMSE scores (mid-region rho = -0.22, p = 0.006; C-terminal rho = -0.19, p = 0.016; N-terminus rho = -0.14, p = 0.069). Conclusion Our novel assays demonstrated good analytical and clinical performance. CSF β-syn reliably indicates early synaptic degeneration in AD. The mid-region assay uniquely differentiated SCD-AD from AD-dem, showing promise for early disease detection.
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spelling doaj-art-83aaa80dc40a4397af6c080410f99bb32025-08-20T03:18:30ZengBMCAlzheimer’s Research & Therapy1758-91932025-04-0117111610.1186/s13195-025-01716-8Novel CSF β-synuclein-specific assays signal early synaptic degeneration in Alzheimer’s diseaseSherif Bayoumy0Julie Goossens1Charlotte De Rocker2Senna Y. Sie3Nolan J. Barrett4Wiesje M. van der Flier5Charlotte E. Teunissen6Eugeen Vanmechelen7Inge M. W. Verberk8Neurochemistry Laboratory, Department of Laboratory Medicine, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam NeuroscienceADx NeuroSciences NVADx NeuroSciences NVNeurochemistry Laboratory, Department of Laboratory Medicine, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam NeuroscienceNeurochemistry Laboratory, Department of Laboratory Medicine, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam NeuroscienceAlzheimer Center, Department of Neurology, UMC, Vrije Universiteit AmsterdamNeurochemistry Laboratory, Department of Laboratory Medicine, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam NeuroscienceAlzheimer Center, Department of Neurology, UMC, Vrije Universiteit AmsterdamNeurochemistry Laboratory, Department of Laboratory Medicine, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam NeuroscienceAbstract Background Beta-synuclein (β-syn), measured at N-terminal epitopes, is an emerging cerebrospinal fluid (CSF) biomarker for synaptic degeneration in Alzheimer's disease (AD). Targeting the mid-region or C-terminus of β-syn may enhance analytical specificity due to the distinct structures of these regions across the synuclein protein family, unlike targeting the N-terminus, which is conserved across the family. This study aimed to confirm that β-syn is a promising CSF biomarker in AD, using novel assays designed to target different regions of β-syn, to investigate whether these regions are differentially affected in AD. Methods We developed two novel CSF β-syn-specific ELISAs targeting mid-region and C-terminus epitopes and assessed their analytical performance. Using these novel assays in combination with the established N-terminus ELISA, we analyzed a proof-of-concept cohort comprising biomarker-confirmed AD (n = 25) and non-AD subjects (n = 25) and a larger clinical cohort (n = 160) from the Amsterdam Dementia Cohort, wich included 41 individuals with subjective cognitive decline (SCD, controls; AD biomarker negative; 64.3 ± 3.3 years, 23 females), 39 with SCD (AD biomarker positive; 65.7 ± 3.1 years, 17 females), 40 with mild cognitive impairment due to AD (MCI-AD; 66.2 ± 2.9 years, 20 females), and 40 with AD dementia (AD-dem; 65.3 ± 3.4 years, 20 females). Results Both the mid-region and C-terminus assays demonstrated reliable analytical performance. All assays consistently detected β-syn in all clinical samples above their limits of detection, with a good average intra-assay coefficient of variation (range of the three assays: 2.7–6.5%CV) in the proof-of-concept cohort and clinical cohort (range of the three assays: 3.9–7.5%CV). CSF β-syn levels, with all the assays, were significantly elevated in all the AD groups compared with the controls in both cohorts. The diagnostic performance of the assays for distinguishing AD patients from controls was comparable (Delong's p > 0.05, AUC 0.71–0.80). Notably, mid-region β-syn significantly differentiated SCD-AD patients from AD-dem patients (p = 0.035) and MCI-AD patients at a trend level. Only mid-region and C-terminal levels correlated with MMSE scores (mid-region rho = -0.22, p = 0.006; C-terminal rho = -0.19, p = 0.016; N-terminus rho = -0.14, p = 0.069). Conclusion Our novel assays demonstrated good analytical and clinical performance. CSF β-syn reliably indicates early synaptic degeneration in AD. The mid-region assay uniquely differentiated SCD-AD from AD-dem, showing promise for early disease detection.https://doi.org/10.1186/s13195-025-01716-8Alzheimer´s diseasePreclinical alzheimer's diseaseCSF biomarkerβ-SynucleinSynaptic degenerationNovel ELISAs
spellingShingle Sherif Bayoumy
Julie Goossens
Charlotte De Rocker
Senna Y. Sie
Nolan J. Barrett
Wiesje M. van der Flier
Charlotte E. Teunissen
Eugeen Vanmechelen
Inge M. W. Verberk
Novel CSF β-synuclein-specific assays signal early synaptic degeneration in Alzheimer’s disease
Alzheimer’s Research & Therapy
Alzheimer´s disease
Preclinical alzheimer's disease
CSF biomarker
β-Synuclein
Synaptic degeneration
Novel ELISAs
title Novel CSF β-synuclein-specific assays signal early synaptic degeneration in Alzheimer’s disease
title_full Novel CSF β-synuclein-specific assays signal early synaptic degeneration in Alzheimer’s disease
title_fullStr Novel CSF β-synuclein-specific assays signal early synaptic degeneration in Alzheimer’s disease
title_full_unstemmed Novel CSF β-synuclein-specific assays signal early synaptic degeneration in Alzheimer’s disease
title_short Novel CSF β-synuclein-specific assays signal early synaptic degeneration in Alzheimer’s disease
title_sort novel csf β synuclein specific assays signal early synaptic degeneration in alzheimer s disease
topic Alzheimer´s disease
Preclinical alzheimer's disease
CSF biomarker
β-Synuclein
Synaptic degeneration
Novel ELISAs
url https://doi.org/10.1186/s13195-025-01716-8
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