Development of a microbial-rich exposure regimen to accelerate translational research using mouse models of Alzheimer's Disease to humans.

项目摘要 多年来积累的证据表明，微生物暴露和随后的免疫反应 在年龄相关神经退行性疾病的发生和进展中发挥重要作用，包括在 阿尔茨海默病(AD)。然而，对这种神经退行性疾病的研究主要是利用遗传小鼠 在超卫生的无特定病原体(SPF)实验室环境中饲养的模型。高度的 经过消毒的SPF环境可防止不经意的微生物暴露，并降低实验变异性。但 如果没有常规的微生物刺激，这些SPF小鼠的免疫系统仍然处于主要的幼稚状态 主要由抗原缺乏经验的免疫细胞群组成的状态。重要的是，这些幼稚的细胞仍然 被隔离在淋巴组织中，不接触到受疾病影响的器官。因此，研究饲养的动物 在SPF条件下，可能掩盖了免疫系统对神经退行性疾病的重要贡献。如果 诚然，这可能是未能将啮齿动物的研究结果转化为人类的一个主要因素，这是 会自然地接触到各种病原体。Beura博士(本申请的合作调查员)已经证明 SPF级小鼠与宠物商店的小白鼠(这里称为“脏”小鼠)不仅有更多的 外周器官中的免疫细胞，与SPF小鼠相比，但其免疫细胞也显示出成熟 更典型的人类免疫系统的特征。基于这些发现和已知的 在AD的免疫系统，我们评估了富含病原体的环境对5XFAD小鼠模型的影响 广告。我们提供的初步数据表明，与SPF相比，脏病患者的免疫系统更强。 5XFAD小鼠。此外，我们的初步数据显示，与SPF相比，6个月大的脏鼠胶质细胞增多。 5XFAD小鼠。虽然这些发现是有希望的，但同居方法有几个缺点，限制了它的 更广泛的部署，包括病原体的可变传播和雄鼠之间的战斗。要克服 在这些限制下，我们开发了一种新的微生物暴露方案，优化了病原体的传播 使雄性和雌性小鼠的免疫系统发生可复制的变化。在这个提案中，我们将使用这个 确定病原体丰富的环境和成熟的免疫增强的贡献的新方案 系统研究AD小鼠淀粉样蛋白病理模型。为了建立这种新的方法，我们将执行 有两个目的的实验。首先，我们将确定病原体丰富的环境对免疫的影响 两种AD淀粉样神经病理模型5XFAD和APPNL-F以及一种AD小鼠模型的成熟 多动症，PS19。其次，我们将在5XFAD中确定AD病理指标的时间和大小， APPNL-F和PS19小鼠暴露在肮脏和SPF条件下。总之，拟议的实验将提供 对AD发病机制的独特见解，揭示富含微生物的独特贡献 环境和成熟的免疫系统。

Project Summary Accumulating evidence over the years suggests that microbial exposure and the ensuing immune response has a large role in the incidence and progression of age-associated neurodegenerative diseases, including in Alzheimer’s Disease (AD). Yet, research on this neurodegenerative disease has primarily utilized genetic mouse models that are reared in ultra-hygienic specific pathogen free (SPF) laboratory environments. The highly sanitized SPF environment prevents inadvertent microbial exposure and reduces experimental variability. But without routine microbial stimulation, the immune system of these SPF mice remains in a predominantly naïve state comprising mostly of antigen-inexperienced immune cell populations. Importantly, these naïve cells remain sequestered in the lymphoid tissues and do not access disease-affected organs. Thus, studying animals reared in SPF conditions may mask important contributions of the immune system to neurodegenerative diseases. If true, this may be a major contributing factor to the failure of translating findings from rodents to humans, which are naturally exposed to a variety of pathogens. Dr. Beura (co-investigator in this application) has demonstrated that SPF mice co-housed with pet store mice (herein referred as “dirty” mice) not only have a higher number of immune cells in peripheral organs, as compared to SPF mice, but their immune cells also display maturation traits that are more typical of the human immune system. Based on these findings and the known role of the immune system in AD, we assessed the impact of a pathogen-rich environment on the 5XFAD mouse model of AD. We present preliminary data demonstrating that the immune system is heightened in dirty compared to SPF 5XFAD mice. Additionally, our preliminary data show increased gliosis in 6-month-old dirty compared to SPF 5XFAD mice. While these findings are promising, cohousing approaches have several shortcomings that limit its wider deployment, including variable transmission of pathogens and fighting among male mice. To overcome these limitations, we developed a new microbial exposure regimen that optimizes pathogen transmission leading to reproducible changes in the immune system of both male and female mice. In this proposal, we will use this novel regimen to define the contribution of a pathogen-rich environment and matured plus heightened immune system on AD mouse models of amyloid pathology. To establish this novel approach, we will perform experiments in two aims. First, we will determine the impact of a pathogen-rich environment on immune maturation in two mouse models of AD amyloid neuropathology, 5XFAD and APPNL-F, and a mouse model of AD tauopathy, PS19. Second, we will determine the timing and magnitude of AD pathological indices in 5XFAD, APPNL-F and PS19 mice exposed to dirty and SPF conditions. Together, the proposed experiments will provide unique insights about the underpinning of AD pathogenesis and reveal unique contributions of a microbe-rich environment and matured immune system.