ALTERATIONS OF MICROGLIAL PHENOTYPE AND FUNCTION IN AGING AND ALZHEIMER'S DISEASE

阿尔茨海默病(AD)与淀粉样斑块附近的小胶质细胞活化有关，既有神经毒性和促炎介质的释放所致的有害结果，也有淀粉样蛋白吞噬所致的有益影响。越来越多的人认识到，与正常衰老相比，阿尔茨海默病与免疫系统的先天和适应性手臂的损害有关。作为关键的先天免疫细胞，小胶质细胞衰老可能参与神经退行性疾病的发生发展。外周巨噬细胞和小胶质细胞可以采取不同的刺激依赖激活状态，称为经典激活和交替激活，具有不同的相关功能。这些不同的小胶质细胞激活状态在AD发病机制和病程中的作用还知之甚少。这一建议将检验这一假设，即小胶质细胞的激活模式和表型在健康和病理性衰老中受到不同的影响，并有助于AD患者淀粉样蛋白吞噬功能的受损。我们将首先通过将培养的人死后小胶质细胞暴露在适当的细胞因子刺激下，建立经典和替代激活状态的微阵列基因特征。利用流式细胞术、实时荧光聚合酶链式反应和 免疫组织化学技术，然后我们将比较来自无AD病理的老年患者、轻度AD病理但无痴呆的老年患者和痴呆AD患者的小胶质细胞的激活模式和潜力。我们预计经典激活潜力不会有差异，但替代激活随着年龄和疾病的增加而下降。最后，我们将通过进行淀粉样蛋白吞噬试验，并测量趋化因子、细胞因子和神经营养因子的释放，来评估这些患者组之间激活状态依赖的功能差异。总之，这些研究将有助于我们理解不同的小胶质细胞的功能和激活模式，将开始阐明衰老和疾病脑中的小胶质细胞在体外对细胞因子刺激的顺应性程度，并将指出在体内调节小胶质细胞表型的潜在治疗手段。

Alzheimer's disease (AD) is associated with activation of microglia in the vicinity of amyloid plaques with both detrimental results due to release of neurotoxic and pro-inflammatory mediators and beneficial effects due to amyloid phagocytosis. It is increasingly recognized that compared to normal aging, AD is associated with impairment of both innate and adaptive arms of the immune system. As key innate immune cells, microglial senescence may contribute to the development or progression of neurodegenerative diseases. Peripheral macrophages and microglia can adopt different stimulus-dependent activation states, termed classical and alternative activation, with different associated functions. Little is known about the contribution of these different microglial activation states to AD pathogenesis and disease course. This proposal will test the hypothesis that microglial activation patterns and phenotypes are differentially affected in healthy and pathological aging and contribute to impaired amyloid phagocytosis In AD. We will first establish a microarray gene signature for classical and alternative activation states by exposing cultured postmortem human microglial cells to appropriate cytokine stimuli. Using flow cytometry, real-time PCR and immunohistochemical techniques, we will then compare the activation pattern and potential of microglia derived from aged patients with no AD pathology, mild AD pathology but no dementia and from demented AD patients. We expect to see no differences in classical activation potential but an age- and disease-dependent decline in alternative activation. Lastly, we will evaluate activation-state dependent functional differences between these patient groups by performing amyloid phagocytosis assays, and measuring the release of chemokines, cytokines and neurotrophic factors. Together these studies will contribute to our understanding of distinct microglial functions and activation patterns, will begin to elucidate the degree to which microglia from aged and diseased brain are amenable to cytokine stimulation in vitro and will point to potential therapeutic means of modulating microglial phenotype in vivo.