Project 2 Title: The brain brush border and microglial activation in response to ethanol

摘要 在发育或成年期间接触酒精可能会导致大脑损伤。酗酒 在美国，消费是一个日益严重的问题，特别是在青少年和年轻人中，他们的大脑 正在持续发育，因此更容易受到酗酒对大脑功能的有害影响。 临床和临床前证据都表明，小胶质细胞（大脑的常驻免疫细胞）发挥着关键作用 调节酒精引起的神经毒性。事实上，酗酒后的大脑炎症会损害大脑 发育和功能。此外，小胶质细胞的激活促进了小鼠模型的饮酒偏好 长期接触酒精。然而，小胶质细胞介导的细胞或分子机制 成人或青少年大脑中的神经元损伤和对酒精的反应改变动物行为尚未发生 已被识别。此外，酒精对小胶质细胞-神经元结构或功能相互作用的影响 目前还没有研究过，主要是由于技术限制。我们之前进行了体内成像 使用双光子显微镜发现了小胶质细胞的动态性质，提供了第一个实时 展示其组织监视功能。我们还揭示了他们以前未知的快速能力 对微环境的变化做出反应。在系统性炎症挑战之后，小胶质细胞变得 激活，并增加它们与周围脑组织的相互作用。急性和慢性酒精暴露 全身性增加促炎细胞因子，进而直接或间接影响血脑 屏障（BBB）完整性，并促进不同大脑区域的神经炎症和神经毒性作用。我们的 过量乙醇暴露模型的初步结果显示小胶质细胞激活、血脑屏障破坏和 小鼠前额皮质（PFC）神经元损失，该大脑区域与酒精引起的损伤有关 人类。此外，单核细胞特异性删除 MyD88（Toll 样受体 4 下游的关键接头蛋白） 消除乙醇滥用后的小胶质细胞活化、血脑屏障损伤和神经元损失，并防止乙醇- 诱导小鼠损伤。基于这些发现，我们提出的研究将检验以下假设： 增加乙醇暴露会导致局部血脑屏障损伤和小胶质细胞激活，这是 神经元网络的区域结构和功能破坏，以及酒精引起的行为 损伤。

ABSTRACT Exposure to alcohol during development or adulthood may result in damage to the brain. Binge alcohol consumption is a growing problem in the US, particularly among adolescents and young adults whose brains are continuing to develop and are thus more susceptible to the harmful effects of binge drinking on brain function. Both clinical and preclinical evidence suggest that microglia –the brain’s resident immune cells– play a key role in modulating alcohol-induced neurotoxicity. Indeed, brain inflammation following alcohol binge can impair brain development and function. In addition, activation of microglia promotes drinking preference in mouse models of chronic alcohol exposure. However, the cellular or molecular mechanisms through which microglia could mediate neuronal damage and alter animal behavior in response to alcohol in the adult or the adolescent brain have not been identified. Moreover, the effects of alcohol on microglia-neuronal interactions at the structural or functional level have not been studied, mostly due to technological limitations. We previously performed in vivo imaging using two-photon microscopy and discovered the dynamic nature of microglia, providing the first real-time demonstration of their tissue surveillance function. We also revealed their previously unknown ability to rapidly respond to changes in their microenvironment. Following systemic inflammatory challenges microglia become activated, and increase their interactions with the surrounding brain tissue. Acute and chronic alcohol exposure increases pro-inflammatory cytokines systemically, which can in turn directly or indirectly affect blood-brain barrier (BBB) integrity, and promote neuro-inflammatory and neurotoxic effects in different brain regions. Our preliminary results in models of excessive ethanol exposure show microglial activation, BBB disruption, and neuronal loss in the prefrontal cortex (PFC) of mice, a brain region implicated in alcohol-induced impairments in humans. Also, monocyte-specific deletion of MyD88, a key adaptor protein downstream of Toll-like receptor 4, abrogated microglial activation, BBB damage, and neuronal loss following ethanol abuse, and prevented ethanol- induced impairments in mice. Based on these findings, our proposed studies will test the hypotheses that increasing ethanol exposure causes localized BBB damage and microglial activation, which is required for regional structural and functional disruption of neuronal networks, and for alcohol-induced behavioral impairments.