新型非甾体抗炎药基于TIR/NF-kB信号通路抗阿尔茨海默病神经炎症的机制研究

AD accounts for most cases of dementia that are diagnosed after the age of 60 years of life. Along with our country has entered the aging society, alzheimer's disease (AD) cause of dementia threat the life quality and health of old people. It will become a serious health and social problem. Although there is one hundred years of research, A more profound understanding of the AD, but its exact pathogenesis is still unclear. AD brains show two characteristic lesions: extracellular deposits of β-amyloid peptides, so called neuritic or senile plaques, and the intracellular neurofibrillary tangles (NFT) of hyperphosphorylated tau protein. Although Aβ has been considered to play a key role in AD pathogenesis, it remains still uncertain whether Aβ plaques and NFT are causative for AD. The eventual deposition of Aβ and NFT formation may not account for all clinical symptoms of AD. Inflammatory changes are observed in AD brain overall, particularly at the amyloid deposits, which are rich in activated microglia. Once stimulated, the microglia release a wide variety of proinflammatory mediators including cytokines, complement components, various free radicals and nitric oxide (NO), all of which potentially contribute to further neuronal dysfunction and eventually death. These create and feed a vicious cycle that could be essential in the pathological progression of AD. According to the literature of inflammation in AD and our previous research about neuroinflammation, we hypothesis that neuroinflammation is a early events in pathogenesis of AD. Over 30 epidemiologic studies have evaluated the possibility that anti-inflammatory drug use might reduce risk or delay onset of AD, with the vast majority reporting beneficial effects. Moreover, a meta-analysis of a subset of these reports in which duration of use datawere available showed that longer periods of nonsteroidal anti-inflammatory drugs (NSAIDs) use decreased risk in a duration-dependent manner. There is a clear evidence that TLR4 can trigger the amyloid-binduced activation of murine microglia and human monocytes . Several research approaches have confirmed that TLR4 mediates the neurotoxicity induced by microglia, both in vivo and in vitro. As one of the key targets of NSAIDs, cyclooxygenases were first strongly implicated in AD by epidemiologic studies of long term NSAID use, wherein such long term use reduced AD risk by half. A role in the regulation of immune and inflammatory responses was suggested by the findings that PPARγ is expressed in macrophages and that receptor activation results in the inhibition of various inflammatory events . To illustrate the significance of neuroinflammation for understanding AD, we use the assays of double-transgenic APP/PS1 mice in vivo and primary microglia cells culture in vitro, to clarify the neuroinflammation mechanism of TLR4-NF-κB signaling pathways in AD, and find the therapeutic properties novel NSAID to AD.

Aβ沉积、tau蛋白磷酸化和神经纤维缠结更多地被认为是阿尔茨海默病（AD）老年痴呆的结果，而非原因，大量研究证实神经炎症在AD的发生过程中发挥了关键的作用，但神经炎症在AD中发病机制，以及发挥作用的病程阶段仍不明确。临床流行病研究证实非甾体抗炎药明显降低AD的发生，我们的前期研究也显示其具有改善认知障碍和抗神经炎证作用。因此提出神经炎症是AD发病早期事件的假设，TIR-NF-kB信号通路在其中发挥了重要作用。本项目拟采用非甾体抗炎药干预APP/PS1转基因和TLR4基因敲除小鼠试验，结合基因转染和沉默等手段，利用免疫荧光、Western blot和RT-PCR等技术，探索非甾体抗炎药在治疗AD中的作用特点与规律、神经炎症在AD发病中的作用等问题，对阐明非甾体抗炎药抗AD炎症的作用机制和TLR4-NF-kB信号通路在AD发生中的神经炎症机制有重要意义，为AD的抗炎治疗提供新的策略与思路。

人口老龄化是当今世界非常突出的社会问题，而我国人口正在快速进入老龄化社.会，随着人口老龄化而出现的健康问题是我们必须要面对的重要社会问题，特别是与年龄密切相关神经退行性疾病，如老年痴呆症，阿尔茨海默病将成为威胁老年人健康的最严重疾病之一。神经炎症机制近年来成为了研究AD 病因学的热点，它贯穿于阿尔茨海默病发生发展的整个过程。目前，神经炎症是阿尔茨海默病的重要发病原因的假说已经得到了大家的广泛认可。虽然流行病学研究让我们看到了非甾体抗炎药治疗AD 的曙光，但是，临床治疗研究却得到了令人失望的结果。本项目的目的就是基于新型非甾体抗炎药MSL，研究抗炎治疗AD的特点和规律，发现可能的作用机制，为AD的抗炎治疗提供理论基础。.我们的研究发现早期给予非甾体抗炎药MSL治疗APP/PS1转基因AD小鼠，可以明显改善AD小鼠的学习记忆能力，这种作用一方面是通过调控TLR4-NF-κB通路抑制小胶质细胞的活化，发挥抗神经炎症的作用，同时减少Aβ在脑内的沉积。另一方面我们的研究还显示，神经元焦亡是AD发生过程中神经炎死亡的重要方式，这种神经元焦亡可能的通路是神经炎症导致神经元上P2X7R表达增高，诱发NLRP3炎症小体的活化，激活Caspas-1，诱发前炎性因子pro-IL-1β和pro-IL-18的成熟，膜上GSDMD被裂解，细胞膜破裂，炎症因子释放。而MSL通过保护神经炎线粒体的功能，抑制JNK和p38MAPK的磷酸化，非选择性抑制COX表达和PGE2分泌，保护了神经元的损伤和焦亡，从而起到了抑制AD发展，改善学习记忆的作用。.AD的治疗目前仍然是一个难点，本研究为AD的抗炎治疗提供了一种新的思路，早期进行抗炎治疗可能是一种可以尝试的方法。