Towards understanding the role of immune regulation of Apolipoprotein E function in Alzheimer's disease proteostasis

我们建议的目标是确定主要调节细胞因子白介素10(IL10)在调节 以载脂蛋白E(ApoE)亚型依赖的方式在阿尔茨海默病(AD)小鼠模型中的蛋白稳定。 我们的建议解决了与理解AD发病机制相关的两个关键问题：(1)免疫如何 通路与阿尔茨海默病风险基因如载脂蛋白E相互作用并调节功能，以及(2)我们能利用这一点吗？ 是否有知识干扰IL-10/APOE轴并在AD相关小鼠模型中获得治疗益处？ 我们的初步数据显示，抗炎细胞因子白介素10具有意想不到的负面作用 阿尔茨海默病转基因小鼠模型中Aβ和tau蛋白稳定性的研究这证明了与生俱来的 AD类型神经退行性疾病中的免疫和蛋白稳定，这种相互作用我们称为免疫蛋白稳定。这个 这种免疫蛋白抑制导致AD神经退行性病变的机制(S)尚不清楚； 研究免疫蛋白稳定的机制可以使我们能够设计针对这种免疫生物疗法 信号通路。 我们观察到，在APP转基因小鼠中过表达IL-10会恶化Aβ斑块病理和认知功能 通过载脂蛋白E依赖的机制发挥作用。从机制上讲，我们可以将IL-10对β的负面影响归因于 蛋白抑制对小胶质细胞吞噬A-β减少和内源性ApoE表达增加的协同作用 ApoE在不溶性淀粉样斑块中的积聚增加。在我们的研究中，不溶性载脂蛋白E水平的增加 是斑块相关的，与小鼠载脂蛋白E作为Aβ聚集物的病理伴侣的作用一致。阻止 使用针对IL-10的可溶性诱骗受体的IL-10信号转导消除了这一效应并减少了脑淀粉样斑块 负担。在IL-10过表达后，我们观察到类似的载脂蛋白E依赖对tau蛋白稳定的影响 牵张症的独立小鼠模型。从本质上讲，IL-10加速了JNPL3的紧张症并缩短了生存时间 它还促进rTg4510小鼠的前脑神经退行性变和尾部病变。虽然这是一个意想不到的 表型，我们提供了apoE在无细胞系统中与纤维tau特异性相互作用的初步数据， 可以部分解释蛋白质平衡，尽管其他机制，如自噬抑制也需要 考虑过了。在这些稳健的初步数据指导下，我们将实现以下具体目标： 目的1.评估APOE基因是否影响IL10诱导的APP小鼠的蛋白稳定，以及相互作用是否 人载脂蛋白E亚型与Aβ聚合体的结合改变了小胶质细胞对不溶性Aβ的清除。我们将测试IL-2的效果- 表达人APOE蛋白(2或2)的APP转基因小鼠对淀粉样斑块沉积的免疫蛋白抑制作用 3或4)，并提供了对APOE依赖的小胶质细胞摄取和清除聚集的Aβ的机械性见解。我们 预期促进保护性APOE2亚型的表达将在APOE4诱导时起到有益的作用 会产生有害的影响。 AIM2.确定AAV递送的可溶性IL-10受体诱骗(SIL10R1)策略对APP、tau和非 转基因小鼠。鉴于IL-10恶化了Aβ和tau小鼠模型中的蛋白稳定和AD相关表型， 在这里，我们将测试诱骗受体策略对抗IL-10的有效性。通过阻断IL-10信号，我们预计 诱骗受体策略是一种潜在的可翻译的疾病修饰疗法，同时对抗Aβ和tau蛋白沉积。 Aim3.复制和扩展我们对IL-10过度表达作为tau病理驱动因素的研究。在这里，使用AAV 工具包，和系统生物学方法，我们建议重现我们对IL-10/APOE依赖的蛋白平衡的观察 在控制良好和具有行为特征的tau转基因队列中的表型，并进一步提供了对 IL-10/APOE轴的这种淀粉样变性的可能机制。 这项建议的优势在于新的调查员之间的团队合作，并继续致力于研究 阿尔茨海默病小鼠模型的神经免疫轴和一位在创造转基因AD方面经验丰富的研究人员 老鼠模型。我们希望这项提议将增强我们对复杂的免疫信号级联的了解。 AD蛋白稳定和发现针对APOE调节的蛋白稳定的可翻译免疫诱骗受体策略。

The goal of our proposal is to determine the role of the master regulatory cytokine, Interleukin 10 (IL10), in regulating proteostasis in mouse models of Alzheimer’s disease (AD) in an Apolipoprotein E (ApoE) isoform dependent manner. Our proposal addresses two key questions that are relevant to understanding of AD pathogenesis: (1) how does immune pathways interact with and modulate the function of AD risk genes, such as APOE and (2) can we harness this knowledge to disrupt the IL-10/APOE axis and achieve therapeutic benefits in AD-relevant mouse models? Our preliminary data has shown that the anti-inflammatory cytokine Interleukin (IL)-10, has unexpected negative effect on Aβ and tau proteostasis in transgenic mouse models of AD. This demonstrates a complex interplay between innate immunity and proteostasis in AD type neurodegenerative diseases, an interaction we call immunoproteostasis. The mechanism(s) underlying such immunoproteostasis leading to neurodegenerative pathology in AD remain unknown; studying the mechanisms underlying immunoproteostasis can enable us to design immunobiotherapies targeting such signaling pathways. We have observed that overexpression of IL-10 in APP transgenic mice worsens Aβ plaque pathology and cognitive functions via an ApoE-dependent mechanism. Mechanistically, we could attribute the negative effects of IL-10 on Aβ proteostasis to synergistic effects of decreased Aβ phagocytosis by microglia, increased endogenous ApoE expression and enhanced accumulation of ApoE in insoluble amyloid plaques. In our study, the increased level of insoluble ApoE was plaque-associated, consistent with mouse ApoE functioning as a pathological chaperone for Aβ aggregates. Blocking IL-10 signaling using the soluble decoy receptor against IL-10 abrogated this effect and reduced brain amyloid plaque burden. We observed similar ApoE dependent effects on tau proteostasis following IL-10 overexpression in two independent mouse models of tauopathy. Essentially, IL-10 accelerated tauopathy and reduced time to survival in JNPL3 mice; it also promoted forebrain neurodegeneration and tauopathy in the rTg4510 mice. While this was an unexpected phenotype, we provide preliminary data that ApoE specifically interacts with fibrillar tau in a cell free system, which could partially explain the proteostasis, though other mechanisms, such as autophagy inhibition also need to be considered. Guided by these robust preliminary data, we will undertake the following specific aims: Aim 1. Assess whether APOE genotype affects IL10-induced proteostasis in APP mice and evaluate whether interaction of human APOE isoforms with Aβ aggregates alters microglial clearance of insoluble Aβ. We will test the effects of IL- 10 immunoproteostasis on amyloid plaque deposition in an APP transgenic mouse expressing human APOE protein (2 or 3 or 4) and provide mechanistic insights into APOE-dependent microglial uptake and clearance of aggregated Aβ. We expect that promoting expression of the protective APOE2 isoform will have beneficial effects while APOE4 induction will have harmful effects. Aim2. Determine the effects of an AAV-delivered soluble IL-10 receptor decoy (sIL10R1) strategy in APP, tau and non- transgenic mice. Given that IL-10 worsens proteostasis and AD-relevant phenotype in mouse models of Aβ and tau, herein, we will test the efficacy of a decoy receptor strategy against IL-10. By blocking IL-10 signaling, we expect the decoy receptor strategy to be a potentially translatable disease modifying therapy against both Aβ and tau proteostasis. Aim3. Replicate and extend our studies of IL-10 overexpression as a driver of tau pathology. Herein, using the AAV toolkit, and systems biology approach, we propose to reproduce our observations of IL-10/APOE-dependent proteostasis phenotype in a well-controlled and behaviorally-characterized tau transgenic cohort and further provide insights into possible mechanisms underlying such amyloidogenic properties of the IL-10/APOE axis. The strength of this proposal lies in the teamwork between a new investigator with continuing commitment to studying the neuroimmune axis in mouse models of AD and an established investigator with experience in creating transgenic AD mouse models. We expect that this proposal will enhance our knowledge of the complex immune signaling cascades in AD proteostasis and uncover translatable immune decoy receptor strategies targeting APOE-regulated proteostasis.