Fine particulate matter 2.5 (PM2.5), one of the main components of air pollutants, seriously threatens human health. Possible neuronal dysfunction induced by PM2.5 has received extensive attention. However, there is little evidence for the specific biochemical mechanism of neuronal injury induced by PM2.5. Moreover, the pathway for PM2.5 transport from peripheral circulation to the central nervous system (CNS) is still unclear. In the current work, C57BL/6 mice were chronically exposed to ambient PM2.5 for 3, 6, 9, and 12 months. Exposure to ambient PM2.5 resulted in a significant reduction of cognitive ability in mice by Morris water maze test. PM2.5 exposure induced a neuroinflammatory reaction after cognitive impairment, while inflammation in the hypothalamus and olfactory bulb tissue occurred earlier. The expression levels of integrity tight junction proteins in the blood-brain barrier (BBB) were reduced by PM2.5 exposure. Pulmonary inflammation occurred much earlier and diminished at later stage of PM2.5 exposure. The results indicated that chronic exposure to ambient PM2.5 led to cognitive decline in mice; CNS dysfunction may be due to neuroinflammatory reactions; the reduced integrity of the BBB allowed the influence of pulmonary inflammation to neuronal alterations. The work may provide promising therapeutic or preventive targets for air pollution-induced neurodegenerative disease.

中文翻译：

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环境 PM2.5 长期暴露导致小鼠认知能力下降：从肺部炎症到神经元炎症

细颗粒物2.5（PM2.5）是大气污染物的主要成分之一，严重威胁着人类健康。PM2.5可能引起的神经元功能障碍受到广泛关注。然而，关于 PM2.5 引起神经元损伤的具体生化机制的证据很少。此外，PM2.5 从外周循环传输到中枢神经系统 (CNS) 的途径仍不清楚。在目前的工作中，C57BL/6 小鼠长期暴露于环境 PM2.5 中 3、6、9 和 12 个月。通过莫里斯水迷宫试验，暴露于环境 PM2.5 导致小鼠认知能力显着降低。PM2.5 暴露在认知障碍后诱发神经炎症反应，而下丘脑和嗅球组织的炎症发生得更早。PM2.5 暴露降低了血脑屏障 (BBB) 中完整性紧密连接蛋白的表达水平。肺部炎症发生得更早，并在 PM2.5 暴露的后期减弱。结果表明，长期暴露于环境 PM2.5 导致小鼠认知能力下降；中枢神经系统功能障碍可能是由于神经炎症反应；BBB 完整性的降低允许肺部炎症对神经元改变的影响。这项工作可能为空气污染引起的神经退行性疾病提供有希望的治疗或预防目标。5 导致小鼠认知能力下降；中枢神经系统功能障碍可能是由于神经炎症反应；BBB 完整性的降低允许肺部炎症对神经元改变的影响。这项工作可能为空气污染引起的神经退行性疾病提供有希望的治疗或预防目标。5 导致小鼠认知能力下降；中枢神经系统功能障碍可能是由于神经炎症反应；BBB 完整性的降低允许肺部炎症对神经元改变的影响。这项工作可能为空气污染引起的神经退行性疾病提供有希望的治疗或预防目标。