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的激活有关，其有害结果是由于神经毒性和促炎介质的释放，有益效果是由于淀粉样蛋白吞噬。人们越来越认识到，与正常衰老相比，AD与免疫系统先天和适应性臂的损伤有关。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或进展。外周巨噬细胞和小胶质细胞可以采取不同的刺激依赖性激活状态，称为经典激活和替代激活，具有不同的相关功能。这些不同的小胶质细胞激活状态对阿尔茨海默病的发病机制和病程的贡献知之甚少。该提案将验证小胶质细胞激活模式和表型在健康和病理性衰老中受到不同影响的假设，并有助于AD中淀粉样蛋白吞噬功能受损。我们将首先通过将培养的死后人类小胶质细胞暴露于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标记。采用流式细胞术，实时PCR和

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.