Alzheimer's disease (AD) is a debilitating neurodegenerative disorder characterized by brain aggregation of β-amyloid (Aβ) peptides and phosphorylated tau (P-tau) proteins. Extracellular vesicles (EVs) can be isolated and studied for potential roles in disease. While several studies have tested plasma-derived EVs in AD, few have analyzed EVs from cerebrospinal fluid (CSF), which are potentially more closely related to brain changes. This study included 20 AD patients and 20 cognitively unimpaired (CU) participants. Using a novel EV isolation method based on acoustic trapping, we isolated and purified EVs from minimal CSF volumes. EVs were lysed and analyzed by immunoassays for P-tau217 and P-tau181. Isolation was confirmed through transmission electron microscopy and the presence of EV-specific markers (CD9, CD63, CD81, ATP1A3). Nanoparticle tracking analysis revealed a high variance in EV distribution. AD patients exhibited increased P-tau181 and decreased P-tau217 in EVs, leading to a higher EV P-tau181/P-tau217 ratio compared to CU. No significant differences in EV counts or sizes were observed between AD and CU groups. This study is the first to use acoustic trapping to isolate EVs from CSF and demonstrates differential P-tau content in AD-derived EVs, warranting further research to understand the relationship between these EV changes and brain pathology.
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http://dx.doi.org/10.1038/s41598-024-75406-0 | DOI Listing |
Background: Phosphorylated tau (p-tau) 217 is a promising blood biomarker for Alzheimer's disease (AD). However, most p-tau217 assays have been validated solely in ethylenediaminetetraacetic acid (EDTA) plasma, leaving the clinical applicability of serum p-tau217 largely unexplored despite serum being a preferred matrix in many clinical laboratories. To address this gap, we compared p-tau217 concentrations and diagnostic performances in matched plasma and serum samples using four research-use-only assays, including three from commercial sources i.
View Article and Find Full Text PDFAlzheimers Res Ther
January 2025
Center for Cognitive and Computational Neuroscience, Complutense University of Madrid, Pozuelo de Alarcón, 28223, Spain.
Background: Changes in amyloid beta (Aβ) and phosphorylated tau brain levels are known to affect brain network organization but very little is known about how plasma markers can relate to these measures. We aimed to address the relationship between centrality network changes and two plasma pathology markers: phosphorylated tau at threonine 231 (p-tau231), a proxy for early Aβ change, and neurofilament light chain (Nfl), a marker of axonal degeneration.
Methods: One hundred and four cognitively unimpaired individuals were divided into a high pathology load (33 individuals; HP) group and a low pathology (71 individuals; LP) one.
Transl Psychiatry
January 2025
Department of Neurology, Tianjin Neurological Institute, Tianjin Medical University General Hospital, Tianjin, China.
Plasma biomarkers have great potential in the screening, diagnosis, and monitoring of Alzheimer's disease (AD). However, findings on their associations with cerebral perfusion and structural changes are inconclusive. We examined both cross-sectional and longitudinal associations between plasma biomarkers and cerebral blood flow (CBF), gray matter (GM) volume, and white matter (WM) integrity.
View Article and Find Full Text PDFGlia
January 2025
Department of Neurology, University of Washington School of Medicine, Seattle, Washington, USA.
Human genetics studies lent firm evidence that microglia are key to Alzheimer's disease (AD) pathogenesis over a decade ago following the identification of AD-associated genes that are expressed in a microglia-specific manner. However, while alterations in microglial morphology and gene expression are observed in human postmortem brain tissue, the mechanisms by which microglia drive and contribute to AD pathology remain ill-defined. Numerous mouse models have been developed to facilitate the disambiguation of the biological mechanisms underlying AD, incorporating amyloidosis, phosphorylated tau, or both.
View Article and Find Full Text PDFHeliyon
December 2024
Department of Medicine, Faculty of Medicine and Health Sciences, and Institute of Neurosciences, University of Barcelona, Barcelona, Spain.
In early-stage Alzheimer's disease (AD) amyloid-β (Aβ) deposition can induce neuronal hyperactivity, thereby potentially triggering activity-dependent neuronal secretion of phosphorylated tau (p-tau), ensuing tau aggregation and spread. Therefore, cortical excitability is a candidate biomarker for early AD detection. Moreover, lowering neuronal excitability could potentially complement strategies to reduce Aβ and tau buildup.
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