Citations

Abstract Background Brain cells secrete extracellular vesicles (EVs) containing signaling and pathological proteins related to Alzheimer's disease (AD) and related disorders. Recent studies demonstrate brain‐derived EVs (BDEVs) contain misfolded tau and are transmissible of tau pathology in the brain. However, the underlying mechanism regarding EV‐mediated tau pathology is still largely uncharacterized. Method We conducted the immuno‐affinity purification of tau in human brain‐derived EVs (BDEVs) isolated from age and sex‐matched 14 AD and 14 CTRL cases and performed tandem mass‐tag mass spectrometry to profile unbiased tau interactome in BDEVs. We used Nanotemper Monolith to validate the interaction of EV‐tau interactors with tau, and super‐resolution microscopy (Nanoimager) to detect their colocalization in a single‐EV level. We next designed siRNAs to silence EV‐tau interactors in SH‐SY5Y cells overexpressing human P301L tau (SH‐SY5Y‐P301Ltau) and assessed tau loading to EVs by Flow Nanoanalyzer. These EVs were tested for their uptake and tau seeding by human iPSC‐derived neurons (iNeurons). We finally tested the inhibitors of identified molecules on BDEV‐mediated tau propagation in vivo . Result A total of 764 proteins were identified in BDEV‐associated tau interactome from CTRL and AD patients. Sixty‐five proteins were significantly downregulated in AD BDEVs; whereas 5 proteins were significantly upregulated in AD BDEVs compared to CTRL BDEVs. The most enriched tau‐interacting proteins were significantly positively correlated with Braak stage. We confirmed the direct binding of candidate proteins to tau with micromolar binding affinities by Monolith, and their colocalization with tau in human BDEVs using Nanoimager. Silencing of candidate molecules in human SH‐SY5Y‐P301Ltau cells showed reduced loading of tau in EVs, their reduced uptake by iNeurons, and tau seeding activities. Finally, intracerebroventricular injection of neutralizing antibody against the most promising target results in reduction of tau pathology in PS19 mice expressing P301S human tau mutant. Conclusion Our study identified tau‐interacting molecules highly enriched in AD BDEVs compared to CTRL BDVs. Silencing of candidate molecule reduced tau loading to the EVs and their uptake by iNeurons and neutralizing antibody suppressed tau dissemination, highlighting them as promising therapeutic targets to halt tau pathology in AD and related tauopathy.

Abstract Background Extracellular vesicles (EVs) are key mediators in transferring pathological proteins associated with Alzheimer's disease (AD). The apolipoprotein E (APOE) gene, particularly the ε4 allele, is a major genetic risk factor for late‐onset AD. However, the influence of APOE genotype on the biological characteristics and cargo composition of brain‐derived extracellular vesicles (BDEVs) in AD remains poorly understood. Method In this study, BDEVs were isolated from human AD temporal cortex with APOE3/3 and APOE4/4 genotypes ( N = 20 / group). Nanoflow cytometry and super‐resolution microscopy were used to evaluate the tau load within these BDEVs. EV‐mediated tau transmission was assessed in aged human Tau KI and APP NL‐G‐F : Tau KI mice in vivo . BDEV uptake and tau seeding were evaluated in iPSC‐derived neurons through live imaging. Additionally, shotgun lipidomics and data independent acquisition proteomics were analyzed lipidome and proteome of BDEVs, respectively. Key molecules linked to APOE genotype were identified through integrated weighted gene co‐expression network and trait correlation analysis. Result APOE4/4 BDEVs exhibited a higher proportion of phosphorylated tau (pS396) at single EV levels. Upon injection of 300pg tau of BDEVs into aged Tau KI and APP NL‐G‐F : Tau KI mice, APOE4/4 BDEVs significantly increased AT8 + phosphorylated tau levels, and induced neuroinflammation in vivo . Moreover, APOE4/4 BDEVs demonstrated stronger neuronal uptake and tau transfer compared to APOE3/3 BDEVs, impairing the neuronal activity of iPSC‐derived neurons. Lipidomic revealed that APOE4/4 BDEVs were significantly more enriched in pro‐inflammatory long‐chain polyunsaturated fatty acids (PUFA) compared to APOE3/3 with Braak stage association. Furthermore, gene ontology pathway analysis using differentially expressed proteins in APOE4/4 BDEVs showed increased activity in oxidative phosphorylation and sterol‐binding. Multi‐omics integrated data revealed that upregulation of PUFA was significantly associated with elevated cell adhesion molecules and ATPase transporter activity with neural cell adhesion molecule as one of key molecule. Notably, neutralizing antibody against the molecule effectively reduced APOE4/4 BDEV internalization and mitigated EV‐mediated tau pathology in recipient cells. Conclusion Our comprehensive analysis suggested that AD APOE4/4 BDEV may enhance transmissibility of tau pathology and neuroinflammation via enriched pro‐inflammatory PUFA and cell adhesion molecules. Targeting these pathways presents a promising therapeutic strategy to mitigate disease progression, particularly in APOE4 individuals.

Abstract Background Neurodegenerative tauopathies, characterized by the aggregation of misfolded tau protein, poses a significant clinical and scientific challenge. Tau interaction with other proteins affects the formation of ‘tau‐seed’ but less is known about its effects on tau‐seed properties. Our previous study revealed that Bassoon (BSN), a presynaptic protein, interacts with tau‐seed, exacerbating its toxicity. A parallel study also associated missense mutations in BSN with tau aggregation in patients, prompting an investigation into the influence of BSN and its mutations in neurodegeneration for potential therapeutic insights. Method We generated a knock‐in mouse model (BSNKI) harboring the disease‐associated p.Pro3866Ala mutation in endogenous Bsn. Cognitive and motor abilities were evaluated throughout the lifespan of heterozygous and homozygous BSNKI mice, along with analyses of BSN and tau patterns, gliosis, and gene expression changes in their brains. Additionally, we conducted single‐nucleic RNA sequencing to identify changes at the cellular level. Result BSNKI mice displayed progressive motor and memory impairments on the rotarod and fear conditioning assays, respectively. At 10 months, their brains displayed somatic BSN and pathological tau accumulation, with the gene expression changes indicating alterations of microglia, classical complement cascade, and synapse pruning pathways, as well as dysregulation of protein quality control pathways. Neuropathological data suggests that the BSN P3866A mutation instigates robust microglia activation, increased microglia‐mediated synapse engulfment, and a co‐deposition of proteasomal subunits with BSN. Furthermore, snRNA‐seq data suggest changes in neuronal populations and cell signaling. Conclusion Our BSNKI mouse model revealed the contributions of BSN P3866A mutation to tau pathogenesis and neurodegeneration. BSNKI animals displayed progressive motor and memory impairments, deposits of endogenous tau and BSN, as well as changes in gene expression and neuronal populations. Notably, BSN likely plays a dual role, promoting tau aggregation and sequestering protein degradation molecules, leading to tau and protein accumulation at the soma and synapse, which in turn could trigger neuroinflammation and other cellular changes. These findings propose BSN as a promising therapeutic target for tauopathies, underscoring the need for further exploration to elucidate underlying mechanisms and therapeutic implications.

Abstract Background We previously identified a novel mechanism describing how pathological tau transfers via extracellular vesicles (EVs) in Alzheimer's disease (AD). Targeting EV secretion to mitigate tau transfer is, therefore, a promising therapeutic approach for AD. P2X purinoreceptor 7 (P2RX7), an ATP‐gated cationic channel predominantly expressed in microglia, regulates the secretion and biogenesis of EVs. Here we investigated the effect of P2rx7 deficiency in PS19 tauopathy mouse model and by proteomic profiling of brain EVs. Method PS19: P2rx7 –/– mice at 9‐10 months of age were tested for fear conditioning and their brain sections were assessed for brain atrophy. Tau pathology was evaluated using ELISA and immunofluorescence against phosphorylated (AT8) and misfolded (Alz50) tau. Brain tissues were further assessed by bulk and single cell RNA‐seq (scRNA‐seq) and brain‐EVs were subjected to proteomic profiling by mass‐spectrometry. P2rx7 –/– mice were intracranially injected with viral vectors expressing P301L tau in neurons and mEmerald‐CD9 in microglia to visualize the secretion of microglial EVs in vivo . Mice conditional knockout (cKO) for P2rx7 in microglia, neurons and astrocytes were injected with a viral vector expressing P301L tau in entorhinal cortex for tau propagation assessment. Result PS19: P2rx7 –/– mice showed significant improvement in contextual and cued memory compared to age‐matched PS19 mice, which was accompanied by preserved cortical and hippocampal volume, and significant reduction of hippocampal synapse loss and tau pathology. By weighted gene co‐expression network analysis (WGCNA) we identified a microglial and EV‐related module strongly correlated with tau pathology which was remarkably downregulated in PS19: P2rx7 –/– mice hippocampus. PS19 mice showed increased secretion of EVs containing tau and mitochondrial proteins in the mouse brain parenchyma, which was significantly downregulated in PS19: P2rx7 –/– mice. scRNA‐seq analysis showed that P2rx7 is required for microglia conversion to inflammatory phenotype with increased expression of EV genes in PS19 mice. P2rx7 deficiency reduced microglial mEmerald‐CD9 + ‐EV secretion in mice expressing P301L tau. Moreover, microglia and neuron‐specific deletion of P2rx7 inhibit tau propagation from the entorhinal cortex to the mouse hippocampus. Conclusion Our study demonstrated a microglial P2RX7‐EV axis with potential implications on neuroinflammation and neurodegeneration associated with tau pathology, further indicating the therapeutic potential of targeting P2rx7 to ameliorate AD progression.

Glioblastoma (GBM), the most common primary malignant brain tumor in adults, has a median survival of 14–15 months despite aggressive treatment. Monitoring relies on MRI, but differentiating tumor progression from pseudo-progression or radiation necrosis remains difficult. Plasma extracellular vesicles (EVs) are emerging as promising non-invasive biomarkers due to their molecular cargos and accessibility. This review evaluates studies that specifically isolated plasma EVs for molecular profiling in GBM diagnosis and monitoring. Biomarkers (miRNA, RNA, DNA, proteins), EV characterization methods, and advancements in enriching tumor-derived EV subpopulations and assessing their diagnostic and prognostic potential are highlighted. Plasma EVs carry diverse cargos, including miRNAs (e.g., miR-21, miR-15b-3p), mRNAs (e.g., EGFRvIII), circRNAs, and proteins (e.g., CD44, GFAP). Composite molecular signatures have achieved sensitivities of 87–100% and specificities of 73–100% for GBM diagnosis. Tumor-derived EVs, enriched using techniques like SEC-CD44 immunoprecipitation, microfluidic platforms, or 5-ALA-induced PpIX fluorescence, enhance biomarker detection. Non-tumor-derived EVs may also reflect GBM’s systemic effects. Challenges include EV heterogeneity, non-EV contamination, and variable biomarker expression across studies. Plasma-EV-based liquid biopsies offer significant potential for GBM monitoring, with advanced enrichment methods improving tumor-specific biomarker detection. Standardizing isolation protocols and validating biomarkers in larger cohorts are critical for clinical translation.

Phonoenterography (PEG) offers a non-invasive and radiation-free technique to assess gastrointestinal activity through acoustic signal analysis. In this feasibility study, 110 high-resolution PEG recordings (44.1 kHz, 16-bit) were acquired from eight healthy individuals, yielding 6314 prominent bowel sound (PBS) segments through automated segmentation. Each event was characterized using a 279-feature acoustic profile comprising Mel-frequency cepstral coefficients (MFCCs), their first-order derivatives (Δ-MFCCs), and six global spectral parameters. After normalization and dimensionality reduction with PCA and UMAP (cosine distance, 35 neighbors, minimum distance = 0.01), five clustering strategies were evaluated. K-Means (k = 5) achieved the most favorable balance between cluster quality (silhouette = 0.60; Calinski–Harabasz = 19,165; Davies–Bouldin = 0.68) and interpretability, consistently identifying five acoustic patterns: single-burst, multiple-burst, harmonic, random-continuous, and multi-modal. Temporal modeling of clustered events further revealed distinct sequential dynamics, with Single-Burst events showing the longest dwell times, random continuous the shortest, and strong diagonal elements in the transition matrix confirming measurable state persistence. Frequent transitions between random continuous and multi-modal states suggested dynamic exchanges between transient and overlapping motility patterns. Together, these findings demonstrate that unsupervised PEG-based analysis can capture both acoustic variability and temporal organization of bowel sounds. This annotation-free approach provides a scalable framework for real-time gastrointestinal monitoring and holds potential for clinical translation in conditions such as postoperative ileus, bowel obstruction, irritable bowel syndrome, and inflammatory bowel disease.

Abstract OBJECTIVE Despite advancements in therapy and improved survival rates for patients with primary central nervous system lymphoma (PCNSL), the optimal management strategy for recurrent or refractory PCNSL (r/r PCNSL) remains undefined. In such cases, repeat brain biopsy is often performed to confirm disease recurrence, though its diagnostic and therapeutic value is uncertain. This study evaluates whether repeat brain biopsy provides new, actionable diagnostic insights that influence treatment decisions. METHODS A retrospective analysis was conducted on patients with a confirmed diagnosis of PCNSL who underwent repeat brain biopsy for suspected recurrent or refractory disease between 2005 and 2023. Patients with a history of other CNS neoplasms, demyelinating disorders, or active systemic disease were excluded. RESULTS Twenty patients met inclusion criteria (55% female), with a mean age at biopsy of 56 years in the PCNSL group and 61 years in the r/r PCNSL group. While the overall distribution of presenting symptoms did not significantly differ (p = 0.2), gait instability, weakness, and cognitive decline were more common in r/r PCNSL. PCNSL more often presented with single lesions, while r/r PCNSL had predominantly multiple lesions (p < 0.05). Periventricular enhancement was significantly more frequent in r/r PCNSL (p < 0.05), though other radiologic features were comparable. Repeat biopsy confirmed DLBCL in 90% of cases; no infections or alternate malignancies were identified. Diagnostic clarification was the primary indication for repeat biopsy. Chemotherapy regimens were altered in 50% of post-biopsy cases, without a corresponding difference in overall survival (p = 0.79). Procedure-related morbidity was observed in three patients (15%). CONCLUSIONS The second biopsy in most cases reaffirmed the original diagnosis of diffuse large B cell lymphoma. Although biopsy results led to treatment adjustments; these changes did not affect overall survival.

Abstract Brain metastases significantly impact neurocognitive function and overall survival. Stereotactic radiosurgery (SRS) is a cornerstone of treatment for patients with limited metastases and expected survival beyond three months. Despite current guidelines, up to 20% of patients with brain metastases undergoing SRS have been reported to die within 90 days. This study retrospectively evaluates prognostic factors associated with 90-day survival after SRS, aiming to improve patient selection. We retrospectively analyzed a cohort of 1,546 patients who underwent Gamma Knife SRS for brain metastases at our institution between 2015 and 2023. One hundred seventy patients who survived fewer than 90 days post-SRS were identified and case-matched to 170 patients who survived over 90 days. Measured variables included patient demographics, tumor characteristics, treatment history, functional status, and control of the primary cancer. We modeled post-SRS 90-day survival using binomial and multivariate logistic regression. Multivariate analysis highlighted Karnofsky Performance Status (KPS) < 70 (OR: 17.4, p < 0.001), prior whole brain radiation (OR: 6, p = 0.004), and focal neurological deficits (OR: 3.02, p = 0.003) as significant predictors of early deaths, while CNS progression before SRS (OR: 0.22, p < 0.001) and control of systemic cancer (OR: 0.556, p = 0.002) were associated with a less than 90-day survival. The predictive model demonstrated acceptable performance with an area under the curve (AUC) of 0.85, accuracy of 80%, sensitivity of 87%, and specificity of 71%. Key predictors of 90-day survival following SRS for brain metastases include functional status (KPS), control of systemic cancer, CNS progression status, and focal neurologic deficits. These findings are complementary factors that can assist in making decisions and SRS patient selection.

Human factors/ergonomics (HF/E) is increasingly recognized as critical to improve patient safety, quality of care and health care professional wellbeing; in particular, much HF/E work has focused on surgery and surgical teams. However, conducting research and practicing in health care broadly, and the operating room (OR) specifically, requires specialized knowledge, skills and experience. HF/E professionals trained in other application areas may face challenges in transitioning due to the specialized knowledge required, regulatory considerations, and complex sociotechnical systems in the OR. This panel is designed for HF/E students, practitioners and researchers who are interested in expanding their work to the OR, procedural suites or modeling these for usability studies. The panel will provide attendees with insights from established HF/E researchers and professionals who study the OR as well as a newcomer to the domain, offering perspectives on career transition challenges, opportunities, and strategies for success.