Dataset Information

Plasma p-tau181, p-tau217, and other blood-based Alzheimer's disease biomarkers in a multi-ethnic, community study.

ABSTRACT:

Introduction

Blood-based Alzheimer's disease (AD) biomarkers provide opportunities for community studies and across ethnic groups. We investigated blood biomarker concentrations in the Washington Heights-Inwood Columbia Aging Project (WHICAP), a multi-ethnic community study of aging and dementia.

Methods

We measured plasma amyloid beta (Aβ)40, Aβ42, total tau (t-tau), phosphorylated tau (p-tau)181, and p-tau217, and neurofilament light chain (NfL) in 113 autopsied participants (29% with high AD neuropathological changes) and in 300 clinically evaluated individuals (42% with clinical AD). Receiver operating characteristics were used to evaluate each biomarker. We also investigated biomarkers as predictors of incident clinical AD.

Results

P-tau181, p-tau217, and NfL concentrations were elevated in pathologically and clinically diagnosed AD. Decreased Aβ42/Aβ40 ratio and increased p-tau217 and p-tau181 were associated with subsequent AD diagnosis.

Discussion

Blood-based AD biomarker concentrations are associated with pathological and clinical diagnoses and can predict future development of clinical AD, providing evidence that they can be incorporated into multi-ethnic, community-based studies.

SUBMITTER: Brickman AM

PROVIDER: S-EPMC8451860 | biostudies-literature | 2021 Aug

REPOSITORIES: biostudies-literature

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Publications

Plasma p-tau181, p-tau217, and other blood-based Alzheimer's disease biomarkers in a multi-ethnic, community study.

Brickman Adam M AM Manly Jennifer J JJ Honig Lawrence S LS Sanchez Danurys D Reyes-Dumeyer Dolly D Lantigua Rafael A RA Lao Patrick J PJ Stern Yaakov Y Vonsattel Jean Paul JP Teich Andrew F AF Airey David C DC Proctor Nicholas Kyle NK Dage Jeffrey L JL Mayeux Richard R

Alzheimer's & dementia : the journal of the Alzheimer's Association 20210213 8

<h4>Introduction</h4>Blood-based Alzheimer's disease (AD) biomarkers provide opportunities for community studies and across ethnic groups. We investigated blood biomarker concentrations in the Washington Heights-Inwood Columbia Aging Project (WHICAP), a multi-ethnic community study of aging and dementia.<h4>Methods</h4>We measured plasma amyloid beta (Aβ)40, Aβ42, total tau (t-tau), phosphorylated tau (p-tau)181, and p-tau217, and neurofilament light chain (NfL) in 113 autopsied participants (29 ...[more]

PMID: 33580742

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Project description:BackgroundThe calibrator in immunoassay plays an essential role in diagnosing Alzheimer's disease (AD). Presently, the most well-studied biomarkers for AD diagnosis are three phosphorylated Tau (p-Tau): p-Tau231, p-Tau217, and p-Tau181. Glycogen synthase-3beta (GSK3β)-phosphorated Tau-441 is the most commonly used calibrator for p-Tau immunoassays. However, the batch-to-batch inconsistency issue of the commonly used GSK3β-phosphorylated Tau-441 limits its clinical application.MethodsWe have successfully generated and characterized 61 Tau monoclonal antibodies (mAbs) with distinct epitopes by using the hybridoma technique and employed them as capture or detection antibodies for p-Tau immunoassays. Through chemical synthesis, we synthesized calibrators, which are three peptides including capture and detection antibody epitopes, for application in immunoassays that detect p-Tau231, p-Tau217, and p-Tau181. The novel calibrators were applied to Enzyme-linked immunosorbent assay (ELISA) and Single-molecule array (Simoa) platforms to validate their applicability and establish a range of p-Tau immunoassays.ResultsBy employing the hybridoma technique, 49 mAbs recognizing Tau (1-22), nine mAbs targeting p-Tau231, one mAb targeting p-Tau217, and two mAbs targeting p-Tau181 were developed. Peptides, including recognition epitopes of capture and detection antibodies, were synthesized. These peptides were used as calibrators to develop 60 immunoassays on the ELISA platform, of which six highly sensitive immunoassays were selected and applied to the ultra-sensitive Simoa platform. Remarkably, the LODs were 2.5, 2.4, 31.1, 32.9, 46.9, and 52.1 pg/ml, respectively.ConclusionThree novel p-Tau calibrators were successfully generated and validated, which solved the batch-to-batch inconsistency issue of GSK3β-phosphorylated Tau-441. The novel calibrators exhibit the potential to promote the standardization of clinical AD diagnostic calibrators. Furthermore, we established a series of highly sensitive and specific immunoassays on the Simoa platform based on novel calibrators, which moved a steady step forward in p-Tau immunoassay application for AD diagnosis.

Project description:Studies have shown that women on the Alzheimer's disease (AD) continuum have more pathological tau in the brain and cerebrospinal fluid (CSF), than men. Some studies have found that higher levels of tau biomarkers are more strongly associated with clinical AD, cognitive decline and neurodegeneration in women than in men. Despite major developments in the use of plasma tau phosphorylated at threonine 181 (p-tau181) as an AD biomarker, it is unknown whether these sex differences apply to plasma p-tau181. In 1060 Alzheimer's Disease Neuroimaging Initiative (ADNI) participants (47% women, 73.8 ± 7.6 years old), we examined sex differences in plasma p-tau181 levels and their association with other biomarkers, cognitive decline and incident AD. Linear regressions tested for an effect of sex on plasma p-tau181 levels and for plasma p-tau181 × sex interactions on CSF p-tau181, as well as entorhinal cortex tau, cortical amyloid-β (Aβ) deposition, and brain glucose metabolism, quantified using PET imaging. Linear mixed effects models tested for a sex × baseline plasma p-tau181 interaction on change in cognition over time. Finally, Cox models tested for a sex × plasma p-tau181 interaction on the risk of AD dementia in participants who were free of dementia at baseline. Despite similar plasma p-tau181 levels between sexes, women had lower brain glucose metabolism, greater brain Aβ and entorhinal cortex tau deposition, higher CSF p-tau181 and faster cognitive decline in relation to higher baseline plasma p-tau181 levels compared with men. Among Aβ positive, dementia-free participants, women had higher rates of incident AD dementia associated with increasing baseline plasma p-tau181 levels, relative to men. Our results suggest that sex may impact the clinical interpretation of plasma p-tau181 concentrations. If replicated, these findings could have important implications for the use of plasma p-tau181 as an accessible AD biomarker and screening tool for preventive and therapeutic clinical trials.

Project description:IntroductionWith the advancement of disease-modifying therapies for Alzheimer's disease (AD), validating plasma biomarkers against cerebrospinal fluid (CSF) and positron emission tomography (PET) standards is crucial in both research and real-world settings.MethodsWe measured plasma phosphorylated tau (p-tau)217, p-tau181, amyloid beta (Aβ)1-40, Aβ1-42, and neurofilament light chain in research and real-world cohorts. Participants were categorized by brain amyloid status using US Food and Drug Administration/European Medicines Agency-approved CSF or PET methods.ResultsPlasma p-tau217 and p-tau217/Aβ1-42 demonstrated superior accuracy in detecting brain amyloid pathologies, with area under the curve from 0.94 to 0.97 in all cohorts. Specificity was lower in the real-world cohort but improved significantly by integrating demographic and clinical factors, aligning performance with research cohorts. Additionally, plasma biomarkers exhibited strong correlations with their CSF counterparts and PET standardized uptake value ratios, with significant associations in amyloid-positive participants.DiscussionPlasma p-tau217 and p-tau217/Aβ1-42 are effective diagnostic tools. However, patient demographics, apolipoprotein E ε4 status, and cognitive condition must be considered to improve specificity in the clinical practice.HighlightsPlasma phosphorylated tau (p-tau)217 and p-tau217/amyloid beta (Aβ)1-42 demonstrated exceptional accuracy (area under the curve: 0.94-0.97) in detecting brain amyloid pathologies across both research (Southern China Aging Brain Initiative [SCABI]-1, SCABI-2) and real-world clinical practice (RCP) cohorts. Incorporating patient-specific factors (sex, age, apolipoprotein E ε4, cognitive status) improved diagnostic specificity in the clinical RCP cohort, aligning its performance with that of research cohorts. Plasma biomarkers, particularly p-tau217 and their ratios, showed robust correlations with cerebrospinal fluid biomarkers and positron emission tomography amyloid standardized uptake value ratios, underscoring their value as non-invasive diagnostic alternatives. Plasma p-tau217 and p-tau217/Aβ1-42 proved highly effective in diagnosing amyloid burden, offering a practical solution to bridge research advancements with real-world clinical practice.

Project description:Tau phosphorylated at threonine 181 (p-tau181) measured in blood plasma has recently been proposed as an accessible, scalable, and highly specific biomarker for Alzheimer's disease. Longitudinal studies, however, investigating the temporal dynamics of this novel biomarker are lacking. It is therefore unclear when in the disease process plasma p-tau181 increases above physiological levels and how it relates to the spatiotemporal progression of Alzheimer's disease characteristic pathologies. We aimed to establish the natural time course of plasma p-tau181 across the sporadic Alzheimer's disease spectrum in comparison to those of established imaging and fluid-derived biomarkers of Alzheimer's disease. We examined longitudinal data from a large prospective cohort of elderly individuals enrolled in the Alzheimer's Disease Neuroimaging Initiative (ADNI) (n = 1067) covering a wide clinical spectrum from normal cognition to dementia, and with measures of plasma p-tau181 and an 18F-florbetapir amyloid-β PET scan at baseline. A subset of participants (n = 864) also had measures of amyloid-β1-42 and p-tau181 levels in CSF, and another subset (n = 298) had undergone an 18F-flortaucipir tau PET scan 6 years later. We performed brain-wide analyses to investigate the associations of plasma p-tau181 baseline levels and longitudinal change with progression of regional amyloid-β pathology and tau burden 6 years later, and estimated the time course of changes in plasma p-tau181 and other Alzheimer's disease biomarkers using a previously developed method for the construction of long-term biomarker temporal trajectories using shorter-term longitudinal data. Smoothing splines demonstrated that earliest plasma p-tau181 changes occurred even before amyloid-β markers reached abnormal levels, with greater rates of change correlating with increased amyloid-β pathology. Voxel-wise PET analyses yielded relatively weak, yet significant, associations of plasma p-tau181 with amyloid-β pathology in early accumulating brain regions in cognitively healthy individuals, while the strongest associations with amyloid-β were observed in late accumulating regions in patients with mild cognitive impairment. Cross-sectional and particularly longitudinal measures of plasma p-tau181 were associated with widespread cortical tau aggregation 6 years later, covering temporoparietal regions typical for neurofibrillary tangle distribution in Alzheimer's disease. Finally, we estimated that plasma p-tau181 reaches abnormal levels ∼6.5 and 5.7 years after CSF and PET measures of amyloid-β, respectively, following similar dynamics as CSF p-tau181. Our findings suggest that plasma p-tau181 increases are associated with the presence of widespread cortical amyloid-β pathology and with prospective Alzheimer's disease typical tau aggregation, providing clear implications for the use of this novel blood biomarker as a diagnostic and screening tool for Alzheimer's disease.

Dataset Information

Plasma p-tau181, p-tau217, and other blood-based Alzheimer's disease biomarkers in a multi-ethnic, community study.

Introduction

Methods

Results

Discussion

Publications

Plasma p-tau181, p-tau217, and other blood-based Alzheimer's disease biomarkers in a multi-ethnic, community study.

Similar Datasets

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