Brain-derived extracellular vesicles (EVs) play an active role in Alzheimer's disease (AD), relaying important physiological information about their host tissues. The internal cargo of EVs is protected from degradation, making EVs attractive AD biomarkers. However, it is unclear how circulating EVs relate to EVs isolated from disease-vulnerable brain regions. We developed a novel method for collecting EVs from the hippocampal interstitial fluid (ISF) of live mice. EVs (EV^ISF) were isolated via ultracentrifugation and characterized by nanoparticle tracking analysis, immunogold labelling, and flow cytometry. Mass spectrometry and proteomic analyses were performed on EV^ISF cargo. EV^ISF were 40–150 nm in size and expressed CD63, CD9, and CD81. Using a model of cerebral amyloidosis (e.g., APPswe, PSEN1dE9 mice), we found protein concentration increased but protein diversity decreased with Aβ deposition. Genotype, age, and Aβ deposition modulated proteostasis- and immunometabolic-related pathways. Changes in the microglial EV^ISF proteome were sexually dimorphic and associated with a differential response of plaque associated microglia. We found that female APP/PS1 mice have more amyloid plaques, less plaque associated microglia, and a less robust- and diverse- EV^ISF microglial proteome. Thus, in vivo microdialysis is a novel technique for collecting EV^ISF and offers a unique opportunity to explore the role of EVs in AD.

中文翻译：

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收集海马间质液细胞外囊泡 (EVISF) 的新方法揭示了小胶质细胞 EV 蛋白质组响应 Aβ 病理的性别依赖性变化

脑源性细胞外囊泡 (EV) 在阿尔茨海默病 (AD) 中发挥着积极作用，传递有关其宿主组织的重要生理信息。电动汽车的内部货物免受降解，使电动汽车成为有吸引力的 AD 生物标志物。然而，目前尚不清楚循环中的 EV 与从疾病易感脑区分离出的 EV 有何关系。我们开发了一种从活小鼠海马间质液（ISF）中收集 EV 的新方法。通过超速离心分离EV (EV ^ISF )，并通过纳米颗粒跟踪分析、免疫金标记和流式细胞术进行表征。^{对 EV ISF}货物进行了质谱分析和蛋白质组分析。EV ^ISF大小为 40-150 nm，表达 CD63、CD9 和 CD81。使用脑淀粉样变性模型（例如APPswe、PSEN1dE9小鼠），我们发现蛋白质浓度随着 Aβ 沉积而增加，但蛋白质多样性降低。基因型、年龄和 Aβ 沉积调节蛋白质稳态和免疫代谢相关途径。小胶质细胞 EV ^ISF蛋白质组的变化呈性别二态性，并与斑块相关小胶质细胞的差异反应相关。我们发现雌性 APP/PS1 小鼠具有更多的淀粉样斑块、更少的斑块相关小胶质细胞以及不太稳定和多样化的 EV ^ISF小胶质细胞蛋白质组。因此，体内微透析是一种收集 EV ^ISF的新技术，并为探索 EV 在 AD 中的作用提供了独特的机会。