Dataset Information

Novel tau biomarkers phosphorylated at T181, T217 or T231 rise in the initial stages of the preclinical Alzheimer's continuum when only subtle changes in Aβ pathology are detected.

ABSTRACT: In Alzheimer's disease (AD), tau phosphorylation in the brain and its subsequent release into cerebrospinal fluid (CSF) and blood is a dynamic process that changes during disease evolution. The main aim of our study was to characterize the pattern of changes in phosphorylated tau (p-tau) in the preclinical stage of the Alzheimer's continuum. We measured three novel CSF p-tau biomarkers, phosphorylated at threonine-181 and threonine-217 with an N-terminal partner antibody and at threonine-231 with a mid-region partner antibody. These were compared with an automated mid-region p-tau181 assay (Elecsys) as the gold standard p-tau measure. We demonstrate that these novel p-tau biomarkers increase more prominently in preclinical Alzheimer, when only subtle changes of amyloid-β (Aβ) pathology are detected, and can accurately differentiate Aβ-positive from Aβ-negative cognitively unimpaired individuals. Moreover, we show that the novel plasma N-terminal p-tau181 biomarker is mildly but significantly increased in the preclinical stage. Our results support the idea that early changes in neuronal tau metabolism in preclinical Alzheimer, likely in response to Aβ exposure, can be detected with these novel p-tau assays.

SUBMITTER: Suarez-Calvet M

PROVIDER: S-EPMC7721364 | biostudies-literature | 2020 Dec

REPOSITORIES: biostudies-literature

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Novel tau biomarkers phosphorylated at T181, T217 or T231 rise in the initial stages of the preclinical Alzheimer's continuum when only subtle changes in Aβ pathology are detected.

Suárez-Calvet Marc M Karikari Thomas K TK Ashton Nicholas J NJ Ashton Nicholas J NJ Lantero Rodríguez Juan J Milà-Alomà Marta M Gispert Juan Domingo JD Salvadó Gemma G Minguillon Carolina C Fauria Karine K Shekari Mahnaz M Grau-Rivera Oriol O Arenaza-Urquijo Eider M EM Sala-Vila Aleix A Sánchez-Benavides Gonzalo G González-de-Echávarri José Maria JM Kollmorgen Gwendlyn G Stoops Erik E Vanmechelen Eugeen E Zetterberg Henrik H Blennow Kaj K Molinuevo José Luis JL

EMBO molecular medicine 20201110 12

In Alzheimer's disease (AD), tau phosphorylation in the brain and its subsequent release into cerebrospinal fluid (CSF) and blood is a dynamic process that changes during disease evolution. The main aim of our study was to characterize the pattern of changes in phosphorylated tau (p-tau) in the preclinical stage of the Alzheimer's continuum. We measured three novel CSF p-tau biomarkers, phosphorylated at threonine-181 and threonine-217 with an N-terminal partner antibody and at threonine-231 wit ...[more]

PMID: 33169916

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Project description:ImportancePhase 3 trials of successful antiamyloid therapies in Alzheimer disease (AD) have demonstrated improved clinical efficacy in people with less severe disease. Plasma biomarkers will be essential for efficient screening of participants in future primary prevention clinical trials testing antiamyloid therapies in cognitively unimpaired (CU) individuals with initially low brain β-amyloid (Aβ) levels who are at high risk of accumulating Aβ.ObjectiveTo investigate if combining plasma biomarkers could be useful in predicting subsequent development of Aβ pathology in CU individuals with subthreshold brain Aβ levels (defined as Aβ levels <40 Centiloids) at baseline.Design, setting, and participantsThis was a longitudinal study including Swedish BioFINDER-2 (enrollment 2017-2022) and replication in 2 independent cohorts, the Knight Alzheimer Disease Research Center (Knight ADRC; enrollment 1988 and 2019) and Swedish BioFINDER-1 (enrollment 2009-2015). Included for analysis was a convenience sample of CU individuals with baseline plasma phosphorylated tau 217 (p-tau217) and Aβ42/40 assessments and Aβ assessments with positron emission tomography (Aβ-PET) or cerebrospinal fluid (CSF) Aβ42/40. Data were analyzed between April 2023 and May 2024.ExposuresBaseline plasma levels of Aβ42/40, p-tau217, the ratio of p-tau217 to nonphosphorylated tau (%p-tau217), p-tau231, and glial fibrillary acidic protein (GFAP).Main outcomes and measuresCross-sectional and longitudinal PET and CSF measures of brain Aβ pathology.ResultsThis study included 495 (BioFINDER-2), 283 (Knight ADRC), and 205 (BioFINDER-1) CU participants. In BioFINDER-2, the mean (SD) age was 65.7 (14.4) with 261 females (52.7%). When detecting abnormal CSF Aβ-status, a combination of plasma %p-tau217 and Aβ42/40 showed better performance (area under the curve = 0.949; 95% CI, 0.929-0.970; P <.02) than individual biomarkers. In CU participants with subthreshold baseline Aβ-PET, baseline plasma %p-tau217 and Aβ42/40 levels were significantly associated with baseline Aβ-PET (n = 384) and increases in Aβ-PET over time (n = 224). Associations of plasma %p-tau217 and Aβ42/40 and their interaction with baseline Aβ-PET (%p-tau217: β = 2.77; 95% CI, 1.84-3.70; Aβ42/40: β = -1.64; 95% CI, -2.53 to -0.75; %p-tau217 × Aβ42/40: β = -2.14; 95% CI, -2.79 to -1.49; P < .001) and longitudinal Aβ-PET (%p-tau217: β = 0.67; 95% CI, 0.48-0.87; Aβ42/40: β = -0.33; 95% CI, -0.51 to -0.15; %p-tau217 × Aβ42/40: β = -0.31; 95% CI, -0.44 to -0.18; P < .001) were also significant in the models combining the 2 baseline biomarkers as predictors. Similarly, baseline plasma p-tau217 and Aβ42/40 were independently associated with longitudinal Aβ-PET in Knight ADRC (%p-tau217: β = 0.71; 95% CI, 0.26-1.16; P = .002; Aβ42/40: β = -0.74; 95% CI, -1.26 to -0.22; P = .006) and longitudinal CSF Aβ42/40 in BioFINDER-1 (p-tau217: β = -0.0003; 95% CI, -0.0004 to -0.0001; P = .01; Aβ42/40: β = 0.0004; 95% CI, 0.0002-0.0006; P < .001) in CU participants with subthreshold Aβ levels at baseline. Plasma p-tau231 and GFAP did not provide any clear independent value.Conclusions and relevanceResults of this cohort study suggest that combining plasma p-tau217and Aβ42/40 levels could be useful for predicting development of Aβ pathology in people with early stages of subthreshold Aβ accumulation. These biomarkers might thus facilitate screening of participants for future primary prevention trials.

Project description:BackgroundCurrent AT(N) stratification for Alzheimer's disease (AD) accounts for complex combinations of amyloid (A), tau proteinopathy (T) and neurodegeneration (N) signatures. Understanding the transition between these different stages is a major challenge, especially in view of the recent development of disease modifying therapy.MethodsThis is an observational study, CSF levels of Tau, pTau181, pTau217, Aβ38/40/42, sAPPα/β, BACE1 and neurogranin were measured in the BALTAZAR cohort of cognitively impaired patients and in the Alzheimer's Disease Neuroimaging Initiative (ADNI). Biomarkers levels were related to the AT(N) framework. (A) and (T) were defined in BALTAZAR with CSF Aβ42/40 ratio and pTau217 respectively, and in ADNI with amyloid and tau PET. (N) was defined using total CSF tau in both cohorts.ResultsAs expected, CSF Aβ42 decreased progressively with the AD continuum going from the A-T-N- to the A + T + N + profile. On the other hand, Tau and pTau181 increased progressively with the disease. The final transition from A + T + N- to A + T + N + led to a sharp increase in Aβ38, Aβ42 and sAPP levels. Synaptic CSF biomarkers BACE1 and neurogranin, were lowest in the initial A + T-N- stage and increased with T + and N + . CSF pTau181 and total tau were closely related in both cohorts.ConclusionsThe early transition to an A + phenotype (A + T-N-) primarily impacts synaptic function. The appearance of T + and then N + is associated with a significant and progressive increase in pathological Alzheimer's disease biomarkers. Our main finding is that CSF pTau181 is an indicator of N + rather than T + , and that N + is associated with elevated levels of BACE1 protein and beta-amyloid peptides. This increase may potentially fuel the amyloid cascade in a positive feedback loop. Overall, our data provide further insights into understanding the interconnected pathological processes of amyloid, tau, and neurodegeneration underlying Alzheimer's disease.

Project description:Tau phosphorylation and aggregation are pathological features of Alzheimers disease. Tau phosphorylated at threonine 217 (pT217) and threonine 231 (pT231) are early fluid biomarkers of Alzheimers disease, suggesting early involvement in disease. However, little is known about the specific actions of these types of phosphorylated tau in Alzheimers disease. Here we performed affinity purification mass spectrometry of pT217 and pT231 tau to determine how phosphorylation of specific tau residues alters its interactome in Alzheimers disease post-mortem brain tissue (n=10). These patients were a balanced cohort of APOE e3/e3 and e4/e4 genotypes (n=5 each) to explore how the most significant AD genetic risk factor altered phosphorylated tau interactions. Results were also compared to our previous interactome dataset examining tau phosphorylated at S396/S404 (enriched using the PHF1 antibody) generated using the same cases. pT217 affinity purification mass spectrometry identified 23 interacting proteins (SAINT score > 0.65). pT217 enriched tau had a constrained phosphorylation signature compared to PHF1 enriched tau, but interactors shared significant overlap. The phosphorylation patterns of pT217 enriched tau included lower intensities of phosphorylation at epitopes serine 396 and serine 404 than PHF1 enriched tau, suggesting pT217 tau was at an earlier state of dysregulation. pT217 interacting proteins were most significantly enriched for biological processes involved in protein catabolism, highlighting the CTLH E3 ubiquitin ligase complex as a novel interactor of multiple phosphorylated tau species (5 interacting subunits: WDR26, ARMC8, GID8, RANBP9, MAEA). In APOE e3/e3 cases pT217 significantly interacted with 46 proteins compared to 28 in APOE e4/e4 cases. These interacting proteins were significantly overlapped, with 13 proteins in common (Fishers exact p = 9x10-23). CTLH E3 ubiquitin ligase subunits significantly interacted with phosphorylated tau in both APOE genotypes. pT231 immunoprecipitation failed to sufficiently enrich tau but results are provided in supplementary data. The phosphorylated tau interaction with p62 and the CTLH component WDR26 were validated using co-immunoprecipitation and immunofluorescent microscopy of fixed post-mortem human brain tissue. In conclusion, our results report the interactome of pT217 in human Alzheimers disease brain tissue for the first time and highlight the CTLH complex as a significant novel interactor of multiple types of phosphorylated tau, including those increased early in Alzheimers disease. The mass spectrometric files of this AP-MS experiment are included here.

Dataset Information

Novel tau biomarkers phosphorylated at T181, T217 or T231 rise in the initial stages of the preclinical Alzheimer's continuum when only subtle changes in Aβ pathology are detected.

Publications

Novel tau biomarkers phosphorylated at T181, T217 or T231 rise in the initial stages of the preclinical Alzheimer's continuum when only subtle changes in Aβ pathology are detected.

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