Targeting Abeta phagocytosis by blocking IRAK-M innate immunity in Alzheimer mice

项目总结/摘要 阿尔茨海默病（AD）是最常见的痴呆症，其特征是A肽沉积， “老年性"-淀粉样斑块、神经病理学和神经炎症。Toll样受体（TLR）是生殖细胞系- 由先天免疫系统的细胞编码的病原体传感器，并在淀粉样蛋白中发挥不同的作用 体内平衡TLR通过丝氨酸/苏氨酸IL-1受体相关激酶调节其信号 （伊拉克）。IRAK家族主要由正向调节TLR信号传导的激酶组成，其中显著的 抑制性激酶IRAK-M除外。IRAK-M表达特异于单核细胞谱系的细胞， 包括小胶质细胞，并在控制先天免疫反应方面发挥关键作用。来测试是否 IRAK-M参与脑淀粉样蛋白重塑，我们将IRAK-M缺陷小鼠（IRAK-M-/-）与 过表达突变型人淀粉样前体蛋白的小鼠，APPPS 1小鼠脑缺血模型， 淀粉样变性然后，我们评估了年龄和性别的免疫细胞活化状态和大脑A？负荷， 来自三组的匹配同窝出生的小鼠：APPPS 1-IRAK-M+/+、APPPS 1-IRAK-M-/+和APPPS 1-IRAK-M-/-小鼠。 初步数据显示基因剂量依赖性效应，其中小胶质细胞活化与 IRAK-M等位基因数量。此外，在APPPS 1中，脑实质A？丰度相应地减弱。 IRAK-M-/-小鼠，通过生物化学方法测量。有趣的是，APPPS 1- IRAK-M-/-小鼠脑显示与溶酶体标记物LAMP 1共定位，表明 IRAK-M-/-小胶质细胞介导的A？清除的吞噬机制。该提案旨在测试 IRAK-M的去抑制是否影响淀粉样病变的小胶质细胞重塑。具体目标的重点 1将进一步表征IRAK-M缺陷型阿尔茨海默病小鼠的脑病理学和动物行为。的 拟议的实验将阐明IRAK-M缺陷对阿尔茨海默氏症的小胶质细胞反应的影响， 比如病理学，包括它对认知障碍的影响。然后我们将评估细胞因子/趋化因子 在体内的反应，以确定是否IRAK-M缺陷促进促炎反应或抗炎反应， APPPS 1-IRAK-M-/-小鼠中的小胶质细胞。具体目标2将进一步评估APPPS 1-IRAK中A？的吞噬作用。 M-/-小胶质细胞，并确定IRAK-M在A？吞噬中的功能。申请人是三年级博士生 Terrence Town博士实验室的学生，他一直在AD先天免疫学领域工作， 过去的17年拟议的培训计划概述了一套职业发展活动和科学的 研讨会-例如神经病理学，动物行为学和赠款写作的高级教育-以促进 完成这项工作。

Project Summary/Abstract Alzheimer's disease (AD) is the most common dementia, and is hallmarked by deposition of A¿ peptides as 'senile' ¿-amyloid plaques, neuropathology, and neuroinflammation. Toll-like receptors (TLRs) are germline- encoded sensors of pathogens by cells of the innate immune system and play differential roles in amyloid homeostasis. TLRs transduce their signals through the serine/threonine IL-1 receptor-associated kinase (IRAK). The IRAK family is chiefly comprised of kinases that positively regulate TLR signaling, with the notable exception of the inhibitory kinase, IRAK-M. IRAK-M expression is specific to cells of monocytic lineage, including microglia, and plays a critical role in keeping innate immune responses in check. To test whether IRAK-M participated in cerebral amyloid remodeling, we crossed mice deficient in IRAK-M (IRAK-M-/-) with mice over expressing mutant human amyloid precursor protein, the APPPS1 mouse model of cerebral amyloidosis. We then evaluated the state of immune cell activation and cerebral A¿ burden in age and sex- matched littermates from three groups: APPPS1-IRAK-M+/+, APPPS1-IRAK-M-/+, and APPPS1-IRAK-M-/- mice. Preliminary data showed a gene dose-dependent effect where microglial activation inversely correlated with IRAK-M allele number. Further, brain parenchymal A¿ abundance was correspondingly attenuated in APPPS1- IRAK-M-/- mice as measured by biochemical approaches. Interestingly, confocal imaging of APPPS1- IRAK-M-/- mouse brains revealed A¿ colocalization with the lysosomal marker LAMP1, suggesting a phagocytic mechanism of IRAK-M-/- microglia-mediated A¿ clearance. This proposal is designed to test whether disinhibition of IRAK-M affects microglial remodeling of amyloid pathology. The focus of Specific Aim 1 will be to further characterize brain pathology and animal behavior in IRAK-M deficient Alzheimer mice. The proposed experiments will elucidate the impact of IRAK-M deficiency on the microglial response to Alzheimer- like pathology, including its influence on cognitive impairment. We will then evaluate cytokine/chemokine responses in vivo to determine the whether IRAK-M deficiency promotes pro- or anti-inflammatory reactions of microglia in APPPS1-IRAK-M-/- mice. Specific Aim 2 will further assess phagocytosis of A¿ in APPPS1-IRAK- M-/- microglia and determine the function of IRAK-M in A¿ phagocytosis. The applicant is a third-year doctoral student in the laboratory of Dr. Terrence Town, who has been working in the field of AD innate immunology for the past 17 years. The proposed training plan outlines a set of career development activities and scientific workshops - e.g. advanced education in neuropathology, animal behavior and grant writing - to facilitate completion of this work.