VASCULAR-MEDIATED NEURONAL CELL DEATH IN ALZHEIMER'S

阿尔茨海默病（AD）是一种影响400万美国老年人的神经退行性疾病。我们的假设是，脑微血管通过产生损伤或杀死神经元的可溶性因子参与了AD的发病机制。我们小组最近的数据有力地支持了这一假设，并表明从阿尔茨海默病患者分离的脑微血管和培养损伤的大鼠脑内皮细胞都会分泌导致神经元特异性致命损伤的因子。我们已经产生了单克隆抗体识别和免疫沉淀大鼠内皮细胞来源的毒素。初步实验表明，这些抗体中至少有一种也能免疫沉淀人AD微血管分泌的神经毒性因子，这表明内皮和微血管神经毒素是相同的或密切相关的。这些新发现令人兴奋，并暗示血管系统是大脑中神经毒素的来源。我们的初步数据和单克隆抗体的可用性有力地支持了实现该项目目标的可行性，即纯化和鉴定这些血管源性神经毒性因子。在本项目中，我们的具体目标是：1)纯化和表征大鼠内皮细胞衍生毒性因子（EDTF）；2)克隆EDTF cDNA，确定神经元杀伤的结构基础；3)鉴定抗人AD微血管源性神经毒性因子的多功能单克隆抗体；4)确定神经毒素在正常组织和AD组织中的定位。我们的实验首次确定了血管系统是阿尔茨海默病中神经毒性分子的来源。无论神经毒性因子是已知的还是独特的，正如本项目将评估的那样，阿尔茨海默病脑微血管产生可损伤或杀死神经元的可溶性因子的证明表明，大脑微循环是阿尔茨海默病神经毒性因子的一个新的、未被探索的来源，也是迄今为止未被认识的治疗干预目标。

Alzheimer's disease (AD) is a neurodegenerative disorder affecting 4 million older Americans. Our hypothesis is that brain microvessels contribute to the pathogenesis of AD by producing soluble factors that injure or kill neurons. Recent data from our group strongly support this hypothesis and demonstrate that both brain microvessels isolated from AD patients and rat brain endothelial cells injured in culture secrete factors that cause lethal injury specifically to neurons. We have generated monoclonal antibodies that recognize and immunoprecipitate the rat endothelial cell-derived toxin. Preliminary experiments show that at least one of these antibodies also immunoprecipitates the neurotoxic factor secreted by human AD microvessels, suggesting that the endothelial and microvessel neurotoxins are identical or closely related. These novel findings are exciting and implicate the vasculature as a source of neurotoxins in the brain. The feasibility of achieving the goals of this project, to purify and identify these vascular- derived neurotoxic factors, is strongly supported by our initial data and the availability of monoclonal antibodies. In this project, our specific aims are: 1) to purify and characterize the rat endothelial cell-derived toxic factor (EDTF); 2) to clone the cDNA for EDTF and determine the structural basis for neuronal killing; 3) to characterize multi-functional monoclonal antibodies to the human AD microvessel-derived neurotoxic factor(s); and 4) to determine the localization of neurotoxin(s) in normal and AD tissues. Our experiments are the first to identify the vasculature as a source of neurotoxic molecules in AD. Whether the neurotoxic factor is known or unique, as will be assessed in this project, the demonstration that AD brain microvessels produce soluble factors that injure or kill neurons shows that the cerebral microcirculation is a novel, unexplored source of neurotoxic factors in AD, and a heretofore unrecognized target for therapeutic intervention.