P-tau235: a novel biomarker for staging preclinical Alzheimer's disease.
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SUBMITTER: Lantero-Rodriguez J
PROVIDER: S-EPMC8649868 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Disease-modifying therapies for Alzheimer's disease (AD) would be most effective during the preclinical stage (pathology present, cognition intact) before significant neuronal loss occurs. Therefore, biomarkers that detect AD pathology in its early stages and predict dementia onset and progression will be invaluable for patient care and efficient clinical trial design.AD-associated changes in cerebrospinal fluid (CSF) were measured using two-dimensional difference gel electrophoresis and liquid chromatography tandem mass spectrometry. Subsequently, CSF YKL-40 was measured by enzyme-linked immunosorbent assay in the discovery cohort (n = 47), validation cohort (n = 292) with paired plasma samples (n = 237), frontotemporal lobar degeneration (n=9) [corrected], and progressive supranuclear palsy (PSP; n = 6). Immunohistochemistry was performed to identify source(s) of YKL-40 in human AD brain.Discovery and validation cohorts, showed higher mean CSF YKL-40 in very mild and mild AD-type dementia (Clinical Dementia Rating [CDR] 0.5 and 1) versus control subjects (CDR 0) and PSP subjects. Importantly, CSF YKL-40/A?42 ratio predicted risk of developing cognitive impairment (CDR 0 to CDR > 0 conversion), as well as the best CSF biomarkers identified to date, tau/A?42 and p-tau 181/A?42. Mean plasma YKL-40 was higher in CDR 0.5 and 1 versus CDR 0, and correlated with CSF levels. YKL-40 immunoreactivity labeled astrocytes near a subset of amyloid plaques, implicating YKL-40 in the neuroinflammatory response to A? deposition.These data demonstrate that YKL-40, a putative indicator of neuroinflammation, is elevated in AD and, together with A?42, has potential prognostic utility as a biomarker for preclinical AD.
| S-EPMC3011944 | biostudies-literature
Project description:IntroductionAmyloid beta (Aβ) oligomers are one of the most toxic structural forms of the Aβ protein and are hypothesized to cause synaptotoxicity and memory failure as they build up in Alzheimer's disease (AD) patients' brain tissue. We previously demonstrated that antagonists of the sigma-2 receptor complex effectively block Aβ oligomer toxicity. CT1812 is an orally bioavailable, brain penetrant small molecule antagonist of the sigma-2 receptor complex that appears safe and well tolerated in healthy elderly volunteers. We tested CT1812's effect on Aβ oligomer pathobiology in preclinical AD models and evaluated CT1812's impact on cerebrospinal fluid (CSF) protein biomarkers in mild to moderate AD patients in a clinical trial (ClinicalTrials.gov NCT02907567).MethodsExperiments were performed to measure the impact of CT1812 versus vehicle on Aβ oligomer binding to synapses in vitro, to human AD patient post mortem brain tissue ex vivo, and in living APPSwe /PS1dE9 transgenic mice in vivo. Additional experiments were performed to measure the impact of CT1812 versus vehicle on Aβ oligomer-induced deficits in membrane trafficking rate, synapse number, and protein expression in mature hippocampal/cortical neurons in vitro. The impact of CT1812 on cognitive function was measured in transgenic Thy1 huAPPSwe/Lnd+ and wild-type littermates. A multicenter, double-blind, placebo-controlled parallel group trial was performed to evaluate the safety, tolerability, and impact on protein biomarker expression of CT1812 or placebo given once daily for 28 days to AD patients (Mini-Mental State Examination 18-26). CSF protein expression was measured by liquid chromatography with tandem mass spectrometry or enzyme-linked immunosorbent assay in samples drawn prior to dosing (Day 0) and at end of dosing (Day 28) and compared within each patient and between pooled treated versus placebo-treated dosing groups.ResultsCT1812 significantly and dose-dependently displaced Aβ oligomers bound to synaptic receptors in three independent preclinical models of AD, facilitated oligomer clearance into the CSF, increased synaptic number and protein expression in neurons, and improved cognitive performance in transgenic mice. CT1812 significantly increased CSF concentrations of Aβ oligomers in AD patient CSF, reduced concentrations of synaptic proteins and phosphorylated tau fragments, and reversed expression of many AD-related proteins dysregulated in CSF.DiscussionThese preclinical studies demonstrate the novel disease-modifying mechanism of action of CT1812 against AD and Aβ oligomers. The clinical results are consistent with preclinical data and provide evidence of target engagement and impact on fundamental disease-related signaling pathways in AD patients, supporting further development of CT1812.
| S-EPMC8349378 | biostudies-literature
Project description:IntroductionStaging preclinical Alzheimer disease (AD) by the expected years to symptom onset (EYO) in autosomal dominant AD (ADAD) through biomarker correlations is important.MethodsWe estimated the correlation matrix between EYO/cognition and imaging/CSF biomarkers, and searched for the EYO cutoff where a change in the correlations occurred before and after the cutoff among the asymptomatic mutation carriers of ADAD. We then estimated the longitudinal rate of change for biomarkers/cognition within each preclinical stage defined by the EYO.ResultsBased on the change in the correlations, the preclinical ADAD was divided by EYOs -7 and -13 years. Mutation carriers demonstrated a temporal ordering of biomarker/cognition changes across the three preclinical stages.DiscussionDuration of each preclinical stage can be estimated in ADAD, facilitating better planning of prevention trials with the EYO cutoffs under the recently released FDA guidance. The generalization of these results to sporadic AD warrants further investigation.
| S-EPMC6461496 | biostudies-literature
Project description:Disclosure of Alzheimer's disease (AD) biomarkers to cognitively unimpaired adults are currently conducted only in research settings. Yet, US Food and Drug Administration approval of a disease-modifying treatment for symptomatic individuals, improved understanding of the "preclinical" phase of disease, and advancements toward more accessible biomarker tests suggest such disclosure will increase in frequency, eventually becoming routine in clinical practice. The changing landscape in AD research to focus on biomarkers has generated debate on the validity and clinical utility of disclosure to cognitively unimpaired adults. This article explores the broader social implications of more widespread AD biomarker disclosure-that is, of individuals learning their risk for developing dementia caused by AD. We identify 10 challenges and offer preliminary solutions. As the field continues to evolve, it is essential to anticipate and address these broader ethical, legal, and social implications of disclosure.
| S-EPMC9405485 | biostudies-literature
Project description:Biological staging of individuals with Alzheimer's disease (AD) may improve diagnostic and prognostic work-up of dementia in clinical practice and the design of clinical trials. Here, we created a staging model using the Subtype and Stage Inference (SuStaIn) algorithm by evaluating cerebrospinal fluid (CSF) amyloid-β (Aβ) and tau biomarkers in 426 participants from BioFINDER-2, that represent the entire spectrum of AD. The model composition and main analyses were replicated in 222 participants from the Knight ADRC cohort. SuStaIn revealed in the two cohorts that the data was best explained by a single biomarker sequence (one subtype), and that five CSF biomarkers (ordered: Aβ42/40, tau phosphorylation occupancies at the residues 217 and 205 [pT217/T217 and pT205/T205], microtubule-binding region of tau containing the residue 243 [MTBR-tau243], and total tau) were sufficient to create an accurate disease staging model. Increasing CSF stages (0-5) were associated with increased abnormality in other AD-related biomarkers, such as Aβ- and tau-PET, and aligned with different phases of longitudinal biomarker changes consistent with current models of AD progression. Higher CSF stages at baseline were associated with higher hazard ratio of clinical decline. Our findings indicate that a common pathophysiologic molecular pathway develops across all AD patients, and that a single CSF collection is sufficient to reliably indicate the presence of both AD pathologies and the degree and stage of disease progression.
| S-EPMC10370223 | biostudies-literature
Project description:BackgroundIdeally, disease modifying therapies for Alzheimer disease (AD) will be applied during the 'preclinical' stage (pathology present with cognition intact) before severe neuronal damage occurs, or upon recognizing very mild cognitive impairment. Developing and judiciously administering such therapies will require biomarker panels to identify early AD pathology, classify disease stage, monitor pathological progression, and predict cognitive decline. To discover such biomarkers, we measured AD-associated changes in the cerebrospinal fluid (CSF) proteome.Methods and findingsCSF samples from individuals with mild AD (Clinical Dementia Rating [CDR] 1) (n?=?24) and cognitively normal controls (CDR 0) (n?=?24) were subjected to two-dimensional difference-in-gel electrophoresis. Within 119 differentially-abundant gel features, mass spectrometry (LC-MS/MS) identified 47 proteins. For validation, eleven proteins were re-evaluated by enzyme-linked immunosorbent assays (ELISA). Six of these assays (NrCAM, YKL-40, chromogranin A, carnosinase I, transthyretin, cystatin C) distinguished CDR 1 and CDR 0 groups and were subsequently applied (with tau, p-tau181 and A?42 ELISAs) to a larger independent cohort (n?=?292) that included individuals with very mild dementia (CDR 0.5). Receiver-operating characteristic curve analyses using stepwise logistic regression yielded optimal biomarker combinations to distinguish CDR 0 from CDR>0 (tau, YKL-40, NrCAM) and CDR 1 from CDR<1 (tau, chromogranin A, carnosinase I) with areas under the curve of 0.90 (0.85-0.94 95% confidence interval [CI]) and 0.88 (0.81-0.94 CI), respectively.ConclusionsFour novel CSF biomarkers for AD (NrCAM, YKL-40, chromogranin A, carnosinase I) can improve the diagnostic accuracy of A?42 and tau. Together, these six markers describe six clinicopathological stages from cognitive normalcy to mild dementia, including stages defined by increased risk of cognitive decline. Such a panel might improve clinical trial efficiency by guiding subject enrollment and monitoring disease progression. Further studies will be required to validate this panel and evaluate its potential for distinguishing AD from other dementing conditions.
| S-EPMC3020224 | biostudies-literature
Project description:IntroductionBlood proteins are emerging as candidate biomarkers for Alzheimer's disease (AD). We systematically profiled the plasma proteome to identify novel AD blood biomarkers and develop a high-performance, blood-based test for AD.MethodsWe quantified 1160 plasma proteins in a Hong Kong Chinese cohort by high-throughput proximity extension assay and validated the results in an independent cohort. In subgroup analyses, plasma biomarkers for amyloid, tau, phosphorylated tau, and neurodegeneration were used as endophenotypes of AD.ResultsWe identified 429 proteins that were dysregulated in AD plasma. We selected 19 "hub proteins" representative of the AD plasma protein profile, which formed the basis of a scoring system that accurately classified clinical AD (area under the curve = 0.9690-0.9816) and associated endophenotypes. Moreover, specific hub proteins exhibit disease stage-dependent dysregulation, which can delineate AD stages.DiscussionThis study comprehensively profiled the AD plasma proteome and serves as a foundation for a high-performance, blood-based test for clinical AD screening and staging.
| S-EPMC9292367 | biostudies-literature
Project description:INTRODUCTION:Ascertainment of the pattern and temporal change of biomarkers in preclinical (asymptomatic) sporadic Alzheimer's disease (AD) will increase knowledge about early pathogenesis and facilitate interventional therapeutic trials. METHODS:In this prospective longitudinal study, repeated cerebrospinal fluid (CSF) collections and cognitive evaluations were performed in cognitively healthy elderly individuals during a 9-year period. RESULTS:Low CSF ?-amyloid (A?)42 levels predicted subsequent development of clinical AD 9 years later. Noteworthy, one-third of individuals with pathologically low baseline A?42 levels remained cognitively intact during follow-up. No further decrease in A?42 was seen in those with low levels already at baseline. DISCUSSION:CSF A?42 predicts sporadic AD at least 9 years before dementia onset and has plateaued already at this time. However, many individuals can harbor brain amyloid accumulation over a decade without signs of cognitive deterioration, which could implicate how CSF biomarkers are used to identify preclinical AD in future interventional therapeutic trials.
| S-EPMC4879483 | biostudies-literature
Project description:IntroductionExisting blood-based biomarkers for Alzheimer's disease (AD) mainly focus on its pathological features. However, studies on blood-based biomarkers associated with other biological processes for a comprehensive evaluation of AD status are limited.MethodsWe developed a blood-based, multiplex biomarker assay for AD that measures the levels of 21 proteins involved in multiple biological pathways. We evaluated the assay's performance for classifying AD and indicating AD-related endophenotypes in three independent cohorts from Chinese or European-descent populations.ResultsThe 21-protein assay accurately classified AD (area under the receiver operating characteristic curve [AUC] = 0.9407 to 0.9867) and mild cognitive impairment (MCI; AUC = 0.8434 to 0.8945) while also indicating brain amyloid pathology. Moreover, the assay simultaneously evaluated the changes of five biological processes in individuals and revealed the ethnic-specific dysregulations of biological processes upon AD progression.DiscussionThis study demonstrated the utility of a blood-based, multi-pathway biomarker assay for early screening and staging of AD, providing insights for patient stratification and precision medicine.HighlightsThe authors developed a blood-based biomarker assay for Alzheimer's disease. The 21-protein assay classifies AD/MCI and indicates brain amyloid pathology. The 21-protein assay can simultaneously assess activities of five biological processes. Ethnic-specific dysregulations of biological processes in AD were revealed.
| S-EPMC10984431 | biostudies-literature
Project description:Alzheimer's disease (AD) is a severe neurodegenerative disorder still in search of effective methods of diagnosis. Altered levels of the NMDA receptor co-agonist, d-serine, have been associated with neurological disorders, including schizophrenia and epilepsy. However, whether d-serine levels are deregulated in AD remains elusive. Here, we first measured D-serine levels in post-mortem hippocampal and cortical samples from nondemented subjects (n=8) and AD patients (n=14). We next determined d-serine levels in experimental models of AD, including wild-type rats and mice that received intracerebroventricular injections of amyloid-β oligomers, and APP/PS1 transgenic mice. Finally, we assessed d-serine levels in the cerebrospinal fluid (CSF) of 21 patients with a diagnosis of probable AD, as compared with patients with normal pressure hydrocephalus (n=9), major depression (n=9) and healthy controls (n=10), and results were contrasted with CSF amyloid-β/tau AD biomarkers. d-serine levels were higher in the hippocampus and parietal cortex of AD patients than in control subjects. Levels of both d-serine and serine racemase, the enzyme responsible for d-serine production, were elevated in experimental models of AD. Significantly, d-serine levels were higher in the CSF of probable AD patients than in non-cognitively impaired subject groups. Combining d-serine levels to the amyloid/tau index remarkably increased the sensitivity and specificity of diagnosis of probable AD in our cohort. Our results show that increased brain and CSF d-serine levels are associated with AD. CSF d-serine levels discriminated between nondemented and AD patients in our cohort and might constitute a novel candidate biomarker for early AD diagnosis.
| S-EPMC4471283 | biostudies-literature