The Experimental Study On The Pathogenesis, Diagnosis And Treatment Of Alzheimer's Disease

Background Alzheimer Disease(AD) is a progressive neurodegenerative disorder whose incidences increase with age. The increasing number of aged people confronted with the medical challenges thrown up by this disease, the heavy burden and the financial cost of the disease is unbearable for families and for society. The most frequent manifestations of the disease are memory disorders relating to recent facts. There is then a slow evolution of the symptoms such as aphasia, apraxia and agnosia. The disease is also accompanied by the cognitive disorders. Till now, the pathogenesis of the disease is unclear, and there are also no effective diagnosis or treatment methods. So, all the studies should serve the purpose of clarifying its pathogenesis, improving methods for early diagnosis and measures, and providing the best possible treatment for those suffering from AD.Objective1. To observe the effects and explore the molecular mechanisms of the inflammation induced byβ-amyloid (Aβ) in microglia(MG) and in mice.2. To observe the beneficial outcome of anti-inflammatory effects of LXA4 in the inflammation induced by Aβ, explore the underlying mechanisms of it, and reveal potential therapeutic effect of LXA4 on AD.3. Detection of amyloid plaque in AD transgenic mice with specific nano magnetic biomarkers using magnetic resonance microimaging. Methods1. The tissue of cortex and hippocampus of mice and cultured BV2 cells, were exposed to Aβ1-42 with or without Pyrrolidinedithiocarbamate ammonium (PDTC), then Enzyme linked immunosorbent assay (ELISA) for interleukin-1β(IL-1β) and tumor necrosis factorα(TNFα); Quantitative real time polymerase chain reaction (RT-PCR) for IL-1? and TNF-αmRNA, western blot analyses of IκBαand NF-κB p65. Immunofluorescence analysis of nuclear translocation of protein NF-κB p65.2. The tissue of cortex and hippocampus of mice and cultured BV2 cells, were exposed to Aβ1-42 with or without LXA4, then Enzyme linked immunosorbent assay (ELISA) for interleukin-1β(IL-1β) and tumor necrosis factorα(TNFα); Quantitative real time polymerase chain reaction (RT-PCR) for IL-1βand TNFαmRNA, western blot analyses of IκBαand NF-κB p65. Immunofluorescence analysis of nuclear translocation of protein NF-κB p65.3. To synthesis a specifically targeted nano-iron contrast agent to label the amyloid plaques in the AD brain in vivo, and then injecte it into the APP/PS1 mice and detected using magnetic resonance microimaging (MRI) , and the analysis the correlation between results and the histological stainings in the end.Results1. The protein and mRNA expressions of IL-1βand TNFα, the degradation of IκBα, and translocation of NF-κB p65 subunit into the nucleus were all inhibited by PDTC, and the inhibitory effects were dose dependently elevated2. LXA4 down-regulated the protein expression of IL-1βand TNFα, attenuated the gene expressions of IL-1βand TNFα, inhibited the degradation of IκBα, inhibited translocation of NF-κB p65 subunit into the nucleus in Aβ-stimulated BV2 cells, and the inhibitory effects were dose dependently elevated.3. Plaques could be detected in 6-month-old APP/PS1 mice in vivo by MRI, after injection of the targeted nano-iron contrast agent. Histological stainings and MRI images have been precisely and spatially registered over a circumscribed area of the cortex .Conclusion1. IL-1βand TNFαwere induced by Aβvia the NF-κB signal pathway in BV2 microglial cells.2. LXA4 inhibits the production of IL-1βand TNFαstimulated by Aβvia the NF-κB signal pathway.3. This specifically targeted nano-iron contrast agent can label the amyloid plaques in the AD brain APP/PS1 mice in vivo and can be detected by MRI.Innovation points1. This study reveals the proinflammatory role ofβ-amyloid in microglial cells and in mie, and also and reveal the mechanisms in vitro and in vivo.2. This study reveals unprecedented findings on this topic of the role of LXA4 in suppressing the inflammation induced by Aβin vitro and in vivo, and the underlying mechanisms were discussed. This study also reveals potential therapeutic effect of LXA4 on AD. Therefore, the administration of LXA4 to control the development of AD would be promising.3. To synthesis a specifically targeted nano-iron contrast agent to label the amyloid plaques in the brain of APP/PS1 mice in vivo successfully, and then enable the amyloid plaques be detected using MRI.