👤 Kensaku Kasuga

Plasma phosphorylated tau 217 (p-tau217) has shown strong potential as a blood-based biomarker for detecting amyloid pathology in Alzheimer's disease. This study evaluated the diagnostic and prognostic utility of plasma biomarkers, including p-tau217, in participants from the Japanese Alzheimer's Disease Neuroimaging Initiative (J-ADNI) cohort. We analyzed paired plasma and CSF samples from 172 J-ADNI participants. CSF and plasma biomarkers were quantified using the LUMIPULSE platform, and the same plasma samples were analyzed using the Simoa platform. The diagnostic accuracy for detecting amyloid pathology and the prognostic value of plasma p-tau217 biomarkers were assessed. Associations between plasma p-tau217 and polygenic risk scores (PRS), as well as potential confounding factors, were examined. Plasma p-tau217 levels measured using Lumipulse and Simoa assays were highly correlated (p < 0.001). All plasma p-tau217 assays showed high diagnostic accuracy for CSF Aβ42/Aβ40-defined amyloid pathology (AUC = 0.98). A single cutoff point based on the Youden index for p-tau217 and p-tau217/Aβ42 achieved >90% specificity and >90% sensitivity. The predefined FDA-approved two-cutoff model for p-tau217/Aβ42 was applicable to this cohort. PRS was significantly associated with plasma p-tau217 independently of APOE genotypes. Subjects with higher plasma p-tau217 levels showed a significantly increased risk of conversion to dementia and larger longitudinal cognitive declines. Plasma p-tau217 levels were significantly influenced by the body mass index, estimated glomerular filtration rate, and high-density lipoprotein cholesterol. Plasma p-tau217 and p-tau217/Aβ42 are robust biomarkers for AD diagnosis and prognosis in the Japanese population. Show less

The cortical asymmetry index evaluates the cortical thickness asymmetry between hemispheres. We investigated cortical asymmetry index in asymptomatic and symptomatic mutation carriers of autosomal dominant Alzheimer's disease to explore the brain asymmetry within the Alzheimer's disease continuum. Sixty baseline T1-weighted MRI scans were obtained from the Clinic Barcelona cohort. Baseline and longitudinal MRI data from 564 participants within the dominantly inherited Alzheimer network observational study were used as an independent, confirmatory cohort. Cerebrospinal fluid and plasma neurofilament light chain levels were included when available. Cortical thickness was calculated using Freesurfer and cortical asymmetry index was calculated via an open-source pipeline. Cross-sectional analyses examined cortical asymmetry index differences based on clinical classification and Show less

Extracellular tau has been highlighted in the pathogenesis of Alzheimer disease (AD), which is the most common neurodegenerative disease. Pathological analyses as well as model animal studies suggest that amyloid-β peptide (Aβ) deposition facilitates the spreading of tau aggregation pathology via extracellular tau. However, the precise mechanism of tau secretion remains unknown. Here, we show that the overexpression of amyloid precursor protein (APP) enhances the secretion of tau phosphorylated at threonine 181 in mouse neuroblastoma Neuro2a cells. Moreover, we found that soluble amyloid precursor protein β (sAPPβ), which is generated by β-site APP cleaving enzyme 1 (BACE1), mediates tau secretion. Our results demonstrate that BACE1-mediated cleavage of APP plays pathological roles in AD pathogenesis by not only Aβ production, but by the spreading of tau aggregation pathology via sAPPβ in AD patients. Show less

Biomarkers of Alzheimer's disease (AD) that can easily be measured in routine health checkups are desirable. Urine is a source of biomarkers that can be collected easily and noninvasively. We previously reported on the comprehensive profile of the urinary proteome of AD patients and identified proteins estimated to be significantly increased or decreased in AD patients by a label-free quantification method. The present study aimed to validate urinary levels of proteins that significantly differed between AD and control samples from our proteomics study (i.e., apolipoprotein C3 [ApoC3], insulin-like growth factor-binding protein 3 [Igfbp3], and apolipoprotein D [ApoD]). Enzyme-linked immunosorbent assays (ELISAs) were performed using urine samples from the same patient and control groups analyzed in the previous proteomics study (18 AD and 18 controls, set 1) and urine samples from an independent group of AD patients and controls (13 AD, 5 mild cognitive impairment [MCI], and 32 controls) from the National Center for Geriatrics and Gerontology Biobank (set 2). In set 1, the crude urinary levels of ApoD, Igfbp3, and creatinine-adjusted ApoD were significantly higher in the AD group relative to the control group ( ApoC3 may be a potential biomarker for AD, as validated by ELISA. Further analysis of ApoC3 as a urinary biomarker for AD is warranted. Show less