CLEC7A in microglia biology and Alzheimer's disease

摘要 C型凝集素受体CLEC7A最近已被鉴定为最高度上调的受体之一。 在包括阿尔茨海默病在内的各种神经退行性疾病中由小胶质细胞表达的分子。然而， 目前对CLEC7A在神经变性疾病发病机制中的作用知之甚少。CLEC7A是最好的 以其在真菌感染的保护性免疫的建立中的关键参与而闻名。CLEC7A辅助 通过促进吞噬作用的诱导以及协调生产来消除真菌病原体 促炎细胞因子和活性氧最近的研究还表明，CLEC7A 可以对自身衍生的分子如死细胞表达的膜联蛋白作出反应。然而，与 CLEC7A检测真菌后产生的促炎效应子应答，CLEC7A的参与 内源性衍生的分子在很大程度上已被证明可以触发抗炎和致耐受性免疫反应， 应答在我们的初步研究中，我们发现CLEC7A在5xFAD小鼠模型中的缺失， 阿尔茨海默病导致小胶质细胞向淀粉样β蛋白（A β）斑块的动员增加， 减少A β沉积，改善神经元健康。相反，我们发现，诱导CLEC7A的明显激活， 通过海马注射真菌来源的CLEC7A激动剂的信号传导增强了海马体清除和小胶质细胞 在5xFAD小鼠中激活。鉴于这些集体发现，我们假设CLEC7A对 小胶质细胞功能和A β控制是配体特异性的，其中内源性来源的CLEC7A激活剂 A β淀粉样变性中产生的抑制剂可以抑制有益的小胶质细胞反应和真菌衍生的CLEC7A激动剂 可反过来促进小胶质细胞活化和A β清除。为了验证这个假设，我们首先 彻底定义CLEC7A的生殖细胞消融如何影响阿尔茨海默病相关疾病的进展， 5xFAD小鼠模型（Aim 1）。我们最近产生了新的Clec7a条件性敲除小鼠（Clec7afl/fl 我们将在Aim 2中利用这种新的遗传工具来询问CLEC7A在小鼠中的小胶质细胞特异性作用。 在5xFAD小鼠中控制A β淀粉样变性、神经炎症和脑病理学。在第三个目标中，我们将 研究各种内源性、治疗性和病原体来源的CLEC7A激动剂对 在多种阿尔茨海默病相关的体内小鼠模型以及人类小胶质细胞中的小胶质细胞反应- 就像诱导多能干细胞产生的细胞一样。

ABSTRACT The C-type lectin receptor CLEC7A has recently been identified to be one of the most highly upregulated molecules expressed by microglia in various neurodegenerative disorders, including Alzheimer’s disease. Yet, little is currently known about the role of CLEC7A in neurodegenerative disease pathogenesis. CLEC7A is best known for its critical involvement in the mounting of protective immunity to fungal infections. CLEC7A aids in the elimination of fungal pathogens by promoting the induction of phagocytosis as well as coordinating the production of proinflammatory cytokines and reactive oxygen species. More recent studies have also shown that CLEC7A can respond to self-derived molecules such as annexins expressed by dead cells. However, in contrast to the pro-inflammatory effector responses generated following CLEC7A detection of fungi, engagement of CLEC7A by endogenously-derived molecules has largely been shown to trigger anti-inflammatory and tolerogenic immune responses. In our preliminary studies, we found that deletion of CLEC7A in the 5xFAD mouse model of Alzheimer’s disease leads to increased mobilization of microglia to amyloid beta (A) plaques, decreased levels of A deposition, and improved neuronal health. In contrast, we find that inducing overt activation of CLEC7A signaling via hippocampal injection of a fungal-derived CLEC7A agonist boosts A clearance and microglial activation in 5xFAD mice. Given these collective findings, we hypothesize that the effects of CLEC7A on microglial function and A control are ligand-specific, where endogenously-derived CLEC7A activators generated in A amyloidosis can suppress beneficial microglial responses and fungal-derived CLEC7A agonists can conversely promote microglial activation and A clearance. To test this working hypothesis, we will first thoroughly define how germline ablation of CLEC7A affects Alzheimer’s-related disease progression in the 5xFAD mouse model (Aim 1). We have recently generated novel Clec7a conditional knockout mice (Clec7afl/fl mice) and we will leverage this new genetic tool in Aim 2 to interrogate a microglia-specific role for CLEC7A in controlling A amyloidosis, neuroinflammation, and brain pathology in 5xFAD mice. In our third Aim, we will investigate the effects that various endogenous, therapeutic, and pathogen-derived CLEC7A agonists have on microglial responses in multiple Alzheimer’s disease-related in vivo mouse models as well as in human microglia- like cells generated from induced pluripotent stem cells.