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

项目摘要/摘要 阿尔茨海默病(AD)是最常见的痴呆症，其特点是A肽沉积为 “老年性”--淀粉样斑块、神经病理学和神经炎症。Toll样受体(TLRs)是生殖系- 先天性免疫系统细胞编码的病原体感受器，在淀粉样蛋白中扮演不同的角色 动态平衡。TLRs通过丝氨酸/苏氨酸IL-1受体相关激酶转导信号 (伊拉克)。IRAK家族主要由积极调节TLR信号的激酶组成，值得注意的是 除抑制激酶IRAK-M外，其余均为IRAK-M。IRAK-M的表达是单核细胞系细胞特有的， 包括小胶质细胞，在抑制先天免疫反应方面起着关键作用。来测试一下 IRAK-M参与脑淀粉样蛋白重塑，我们将IRAK-M缺陷小鼠(IRAK-M-/-)与 高表达突变型人淀粉样前体蛋白APPPS1小鼠模型的建立 淀粉样变性。然后，我们评估了免疫细胞的激活状态和年龄和性别的脑A负担- 来自APPPS1-IRAK-M/、APPPS1-IRAK-M-/和APPPS1-IRAK-M-/-小鼠的配对窝产仔数。 初步数据显示了一种基因剂量依赖效应，其中小胶质细胞激活与 IRAK-M等位基因数。此外，在APPPS1-1中，脑实质A？丰度相应地减弱。 用生化方法测定IRAK-M-/-小鼠。有趣的是，APPPS1的共聚焦成像- IRAK-M-/-小鼠大脑显示与溶酶体标记LAMP1共定位，提示 IRAK-M-/-小胶质细胞介导的A？清除的吞噬机制这项提案旨在测试 IRAK-M的解除抑制是否影响淀粉样蛋白病理的小胶质细胞重构。特定目标的焦点 1将进一步表征IRAK-M缺陷阿尔茨海默病小鼠的脑病理和动物行为。这个 拟议的实验将阐明IRAK-M缺乏对阿尔茨海默氏症小胶质细胞反应的影响。 就像病理学一样，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 体内反应以确定IRAK-M缺乏是否促进促炎或抗炎反应 APPPS1-IRAK-M-/-小鼠的小胶质细胞。特异性靶点2将进一步评估APPPS1-IRAK中A？的吞噬作用。 M-/-小胶质细胞，并测定IRAK-M在巨噬细胞吞噬中的作用。申请者是三年级博士。 特伦斯·唐恩博士实验室的学生，他一直在AD天然免疫学领域工作 过去的17年里。拟议的培训计划概述了一套职业发展活动和科学 举办研讨会--例如神经病理学、动物行为和赠款的高级教育--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.