CSF proteome profiling reveals highly specific biomarkers for dementia with Lewy bodies

Diagnosis of dementia with Lewy bodies (DLB) is challenging and biofluid biomarkers specific for DLB are highly needed. Here we use proximity extension-based multiplex assays to establish the specific cerebrospinal fluid (CSF) proteomic changes that underlie DLB in an unprecedented well-characterized cohort of 109 DLB patients, 235 patients with Alzheimeŕs disease (AD) and 190 controls. We identified more than 50 CSF proteins dysregulated in DLB, which were especially related to myelination processes. An enzyme involved in dopamine biosynthesis (L-amino acid decarboxylase, DDC) was the strongest dysregulated protein in DLB (>1.5 fold-change vs.CON or AD; q<1E-16) and could discriminate DLB from controls and AD patients with high accuracy (AUC: 0.91 and 0.81 respectively). We modelled a CSF protein panel containing only seven of these markers, which discriminate DLB from AD with higher performance (AUC: 0.93, 95%CI: 0.86-0.98). We developed custom multiplex assays for six of these markers (DDC, CRH, MMP-3, ABL1, MMP-10 and THOP1); and validated their performance in independent cohorts (n=329; AUCs: 0.68-0.90), including an autopsy cohort (n=76; AUCs: 0.90-0.95). This extensive and unique DLB CSF proteome study depicts specific protein changes underlying DLB pathophysiology. It translates these findings into a custom CSF biomarker panel able to identify DLB patients with high accuracy in different independent cohorts, providing new testing opportunities for diagnostic settings and clinical trials. ### Competing Interest Statement MC has been an invited speaker at Eisai and is an associate editor at Alzheimer, Research & Therapy. LV received a grant for CORAL consortium by Olink. BMT and PJV are inventors on a patent (#WO2020197399A1; owned by Stichting VUmc). D.I. is a Scientific Advisory Board Member for Denali Therapeutics. D.A. participated in advisory boards from Fujirebio-Europe and Roche Diagnostics and received speaker honoraria from Fujirebio-Europe, Roche Diagnostics, Nutricia, Krka Pharmaceutica S.L., Zambon S.A.U. and Esteve Pharmaceuticals S.A. D.A. declares a filed patent application (WO2019175379 A1 Markers of synaptopathy in neurodegenerative disease). WF has performed contract research for Biogen MA Inc, and Boehringer Ingelheim. WF has been an invited speaker at Boehringer Ingelheim, Biogen MA Inc, Danone, Eisai, WebMD Neurology (Medscape), Springer Healthcare. WF is consultant to Oxford Health Policy Forum CIC, Roche, and Biogen MA Inc. WF participated in advisory boards of Biogen MA Inc and Roche. All funding is paid to her institution. WF is member of the steering committee of PAVE, and Think Brain Health. WF was associate editor of Alzheimer, Research & Therapy in 2020/2021. WF is associate editor at Brain. CET has a collaboration contract with ADx Neurosciences, Quanterix and Eli Lilly, performed contract research or received grants from AC-Immune, Axon Neurosciences, Bioconnect, Bioorchestra, Brainstorm Therapeutics, Celgene, EIP Pharma, Eisai, Grifols, Novo Nordisk, PeopleBio, Roche, Toyama, Vivoryon. She serves on editorial boards of Medidact Neurologie/Springer, Alzheimer Research and Therapy, Neurology: Neuroimmunology & Neuroinflammation, and is editor of a Neuromethods book Springer. She had speaker contracts for Roche, Grifols, Novo Nordisk. The rest of the authors declare no competing interest. ### Funding Statement This research is part of the neurodegeneration research program of Amsterdam Neuroscience. Alzheimer Center Amsterdam is supported by Stichting Alzheimer Nederland and Stichting VUmc fonds. The chair of Wiesje van der Flier is supported by the Pasman stichting. The clinical database structure was developed with funding from Stichting Dioraphte. Funding from ZonMW(# 733050509), Alzheimer Nederland and Stichting Diorapthe supported the DEvELOP study. This study was supported by Alzheimer Nederland (CT, MC), ZonMW (#73305095007), Health~Holland, Topsector Life Sciences & Health (PPP-allowance; #LSHM20106) and Instituto de Salud Carlos III (PI20/01330 and AC19/00103 to AL, PI18/00435 and INT19/00016 to DA), Fondo Europeo de Desarrollo Regional (FEDER), Union Europea, Una manera de hacer Europa, and CIBERNED (Program 1, Alzheimer Disease). MC is supported by the attraction talent fellowship of Comunidad de Madrid (2018T2/BMD11885) and PROYECTOS I+D+I2020 Retos de investigacion from the Ministerio Espanol de Ciencia e innovacion (PID2020115613RAI00). WF, AL, and CT are recipient of TAP-Dementia, a ZonMW funded project (#10510032120003) under the Dutch National Dementia Strategy. Collection of patient samples and data from Penn University was supported by different funding sources: National Institute on Aging (P01 AG066597), National Institute on Aging P30-AG072979 (formerly P30AG10124), National Institute on Aging U19AG06241803 (formerly NINDSP50 NS053488 09)). ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The studies were approved by the Institutional Ethical Review Boards of each center (Discovery cohort: VUmc: AD CSF biobank METC number 00-211; University of Pennsylvania: language and cognitive impairment in parkinsons disease and parkinsons disease with dementia or dementia with lewy bodies IRB069801; or under the Parelsnoer initiative 2009-170.) I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes The data that support the findings of this study are available from the authors on reasonable request.