Is Toll-like receptor-3 signaling involved in Alzheimer's disease?

描述(申请人提供)：本项目将研究Toll样受体3(TLR-3)表达的功能后果，因为它与阿尔茨海默病的特征有关。Toll样受体是一个由10个相关的模式识别受体组成的家族，在协调宿主对微生物制剂的防御方面具有多种功能。我们发现TLR-3在AD脑内主要由小胶质细胞表达，特别是那些与斑块相关的小胶质细胞，而其他重要的TLR与胶质细胞无关。由于TLR-3信号可能有不同的后果，我们认为现在是时候在AD和相关的人体模型系统中进行研究了。由于TLR-3主要是一种内体定位的受体，其功能及其激活对AD的影响有待研究。我们根据初步结果提出了一个中心假设，即用TLR-3的配体刺激小胶质细胞和星形胶质细胞将诱导抗炎和保护性反应，并促进A？的清除。由于刺激相关的内体TLR-9被认为是从脑中去除淀粉样蛋白的一种治疗选择，我们推测TLR-3的激活可能会有类似的结果。这个项目的目标是确定小胶质细胞和星形胶质细胞对TLR-3配体在A？存在下的反应的性质。这将在体外从死后大脑的小胶质细胞和星形胶质细胞培养中以及在体外的人脑切片培养中进行研究。我们还将确定长期给予斑块发育转基因小鼠TLR-3配体是否会影响A？负荷和相关的神经病理学。我们将从三个相关的目标来研究这些特性。具体目的1：我们将研究TLR-3激活对人小胶质细胞和星形胶质细胞产生促炎和抗炎细胞因子及神经毒性因子的功能影响。AD和正常脑的培养将在存在和不存在A？的情况下用TLR-3配体刺激。我们将使用抗体阵列来测量细胞反应，并在体外进行神经毒性和神经保护分析，以确定TLR-3刺激的后果。具体目标2：我们将研究人小胶质细胞和星形胶质细胞TLR-3激活对淀粉样β蛋白摄取和降解的功能影响。这两个目标将在体外使用TLR3配体聚IC和/或A？刺激目标1中描述的人小胶质细胞和星形胶质细胞进行。特定目标3；我们将使用两个发生小胶质细胞、星形胶质细胞和神经元相互作用的复杂系统来研究与目标1和2中相同的特征。我们将使用人脑的体外切片培养和开发转基因小鼠的淀粉样蛋白斑块来确定TLR-3激活是促进还是减少炎症和神经元存活，以及增加或减少胶质细胞的摄取和A？的降解。 公共卫生相关性：这项研究与公共卫生的相关性在于，它可以确定阿尔茨海默病炎症的新特征。我们推测，人脑中Toll样受体-3的激活可能是治疗的目标。目前，我们不知道这一信号在阿尔茨海默病中是否需要增强或抑制，这两个特征都有证据；然而，两者都可能是改变神经退行性变中炎症反应路径的重要方法。这些发现不仅与阿尔茨海默氏症有关，还与其他神经退行性疾病有关。

DESCRIPTION (provided by applicant): This project will examine the functional consequences of Toll-like receptor-3 (TLR-3) expression as it relates to features of Alzheimer's disease. Toll-like receptors, which are a family of 10 related pattern recognition receptors, have multiple functions in coordinating host defenses to microbial agents. We identified TLR-3 as being prominently expressed by microglia in AD brains, particularly those plaque-associated, while other significant TLR were not associated with glia. As TLR-3 signaling can have different consequences, we consider it timely to investigate in AD and related relevant human model systems. As TLR-3 is primarily an endosomal localized receptor, its function and the consequence of its activation to AD requires investigation. We have developed a central hypothesis based on preliminary results that stimulation of microglia and astrocytes with ligands for TLR-3 will induce anti-inflammatory and protective responses, and also promote A¿ removal. As stimulation of related endosomal TLR-9 has been suggested as a therapeutic option for removing amyloid from brain, we are positing that TLR-3 activation may have similar outcome. The goal of this project is to identify the nature of microglia and astrocyte responses to TLR-3 ligands in the presence of A¿. This will be investigated in vitro in microglia and astrocyte cultures derived from postmortem brains, and in ex-vivo human brain slice cultures. We will also determine if chronic TLR-3 ligand administration to plaque-developing transgenic mice affects A¿ load and related neuropathology. We will investigate these features in three related aims. Specific Aim 1; We will investigate what are the functional consequences of TLR-3 activation of human microglia and astrocytes on production of proinflammatory and anti-inflammatory cytokines and neurotoxic factors. Cultures from AD and normal brains will be stimulated with a TLR-3 ligand in the presence and absence of A¿. We will use antibody arrays to measure cellular responses, and also in vitro neurotoxicity and neuroprotective assays to determine consequences of TLR-3 stimulation. Specific Aim 2; We will investigate what are the functional consequences of TLR-3 activation of human microglia and astrocytes on uptake and degradation of amyloid beta peptide. Both aims will be carried out in vitro using the TLR3- ligand poly IC and/or A¿ stimulated human microglia and astrocytes described in Aim 1. Specific Aim 3; We will use two complex systems, where interactions of microglia, astrocytes and neurons occur, to investigate the same features as in aims 1 and 2. We will use ex vivo slice cultures of human brains and also amyloid plaque developing transgenic mice to determine whether TLR-3 activation promotes or reduces inflammation and neuronal survival, and increases or decreases glial uptake and degradation of A¿. PUBLIC HEALTH RELEVANCE: The relevance of this research to public health is that it could identify new features of inflammation in Alzheimer's disease. We are positing that activation of Toll-like receptor-3 in the human brain could be a target for treatment. At present, we do not know if this signaling needs to be enhanced or inhibited in Alzheimer's disease, there is evidence for both features; however either could be significant approaches to changing the path of inflammatory responses in neurodegeneration. These findings will not only be relevant for Alzheimer's but other neurodegenerative diseases.