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

描述（由申请人提供）：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中具有多种功能。我们发现TLR-3在AD大脑中的小胶质细胞中显著表达，特别是斑块相关的小胶质细胞，而其他显著的TLR与胶质细胞无关。由于TLR-3信号可以产生不同的后果，我们认为在AD和相关的人体模型系统中进行研究是及时的。由于TLR-3主要是一种内体定位受体，其功能及其对AD激活的影响有待研究。基于初步结果，我们提出了一个中心假设，即TLR-3配体刺激小胶质细胞和星形胶质细胞会诱导抗炎和保护反应，并促进a¿的去除。由于刺激相关的内体TLR-9已被建议作为去除脑淀粉样蛋白的治疗选择，我们假设TLR-3的激活可能具有类似的结果。该项目的目的是确定在A¿存在下小胶质细胞和星形胶质细胞对TLR-3配体的反应的性质。这将在死后大脑的小胶质细胞和星形胶质细胞培养物以及离体人脑切片培养物中进行研究。我们还将确定慢性TLR-3配体给药对斑块发育转基因小鼠是否影响A¿负荷和相关神经病理学。我们将在三个相关的目标中研究这些特征。具体目标1；我们将研究TLR-3激活人类小胶质细胞和星形胶质细胞对促炎和抗炎细胞因子和神经毒性因子产生的功能后果。AD和正常大脑的培养将在a¿存在和不存在的情况下受到TLR-3配体的刺激。我们将使用抗体阵列来测量细胞反应，以及体外神经毒性和神经保护试验来确定TLR-3刺激的后果。具体目标2；我们将研究TLR-3激活人类小胶质细胞和星形胶质细胞对淀粉样蛋白肽摄取和降解的功能后果。这两个目的将在体外使用TLR3-配体poly IC和/或A¿刺激的人小胶质细胞和星形胶质细胞进行。具体目标3；我们将使用两个复杂的系统，其中小胶质细胞、星形胶质细胞和神经元发生相互作用，来研究与目标1和目标2相同的特征。我们将使用离体人脑切片培养和淀粉样斑块培养转基因小鼠来确定TLR-3激活是否促进或减少炎症和神经元存活，以及增加或减少A¿的胶质摄取和降解。

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.