title: Candidate blood proteome markers of Alzheimer's disease onset and progression: a systematic review and replication study.
abstract: A blood-based protein biomarker, or set of protein biomarkers, that could predict onset and progression of Alzheimer's disease (AD) would have great utility; potentially clinically, but also for clinical trials and especially in the selection of subjects for preventative trials. We reviewed a comprehensive list of 21 published discovery or panel-based (> 100 proteins) blood proteomics studies of AD, which had identified a total of 163 candidate biomarkers. Few putative blood-based protein biomarkers replicate in independent studies but we found that some proteins do appear in multiple studies; for example, four candidate biomarkers are found to associate with AD-related phenotypes in five independent research cohorts in these 21 studies: α-1-antitrypsin, α-2-macroglobulin, apolipoprotein E, and complement C3. Using SomaLogic's SOMAscan proteomics technology, we were able to conduct a large-scale replication study for 94 of the 163 candidate biomarkers from these 21 published studies in plasma samples from 677 subjects from the AddNeuroMed (ANM) and the Alzheimer's Research UK/Maudsley BRC Dementia Case Registry at King's Health Partners (ARUK/DCR) research cohorts. Nine of the 94 previously reported candidates were found to associate with AD-related phenotypes (False Discovery Rate (FDR) q-value < 0.1). These proteins show sufficient replication to be considered for further investigation as a biomarker set. Overall, we show that there are some signs of a replicable signal in the range of proteins identified in previous studies and we are able to further replicate some of these. This suggests that AD pathology does affect the blood proteome with some consistency.
authors.affiliation: King's College London, Institute of Psychiatry, London, UK NIHR Biomedical Research Centre for Mental Health and Biomedical Research Unit for Dementia at South London and Maudsley NHS Foundation, London, UK.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Kiddle
authors.forename: Martina
authors.initials: M
authors.lastname: Sattlecker
authors.forename: Petroula
authors.initials: P
authors.lastname: Proitsi
authors.forename: Andrew
authors.initials: A
authors.lastname: Simmons
authors.forename: Eric
authors.initials: E
authors.lastname: Westman
authors.forename: Chantal
authors.initials: C
authors.lastname: Bazenet
authors.forename: Sally K
authors.initials: SK
authors.lastname: Nelson
authors.forename: Stephen
authors.initials: S
authors.lastname: Williams
authors.forename: Angela
authors.initials: A
authors.lastname: Hodges
authors.forename: Caroline
authors.initials: C
authors.lastname: Johnston
authors.forename: Hilkka
authors.initials: H
authors.lastname: Soininen
authors.forename: Iwona
authors.initials: I
authors.lastname: Kłoszewska
authors.forename: Patrizia
authors.initials: P
authors.lastname: Mecocci
authors.forename: Magda
authors.initials: M
authors.lastname: Tsolaki
authors.forename: Bruno
authors.initials: B
authors.lastname: Vellas
authors.forename: Stephen
authors.initials: S
authors.lastname: Newhouse
authors.forename: Simon
authors.initials: S
authors.lastname: Lovestone
authors.forename: Richard J B
authors.initials: RJ
authors.lastname: Dobson
mesh_terms: D000544:Alzheimer Disease / Q000097:blood* / Q000175:diagnosis*; D015415:Biomarkers / Q000097:blood*; D001798:Blood Proteins / Q000378:metabolism*; D018450:Disease Progression; D006801:Humans; D020543:Proteome
chemical_list: D015415:Biomarkers; D001798:Blood Proteins; D020543:Proteome
keywords: Alzheimer's disease; biomarkers; blood; magnetic resonance imaging; nucleotide aptamers; proteome