气道上皮细胞RUNX1调控急性肺损伤肺部炎症机制研究

Mortility of acute lung injury(ALI) remains high at present. Our previous study indicated that the expression of runt-related transcription factor 1(RUNX1) decreased in the lung of mice with ALI induced by LPS or cecal ligation and puncture(CLP). Conditional knockout RUNX1 in airway epithelial cell of mice increased the mortality of ALI induced by LPS. Downregulation of RUNX1 stimulated the expression of inflammatory cytokines in A549 cell. The mechanism of this effect of RUNX1 remains unknown at present. This project will investigate the expression of RUNX1 in airway epithelial cell in ALI/ARDS patients or ALI mice induced by LPS or CLP. The activity of NFκB signal pathway and the interaction between RUNX1 and IKK will also be investigated in airway epitheliel cell after RUNX1 downregulation or upregulation in vitro or in vivo. We will also investigate whether upregulation RUNX1 in airway epithelial cell will improve the mortality and lung inflammation in established ALI indcued by LPS or CLP. All the results will explain the mechanism of RUNX1 regulating lung inflammation through NFκB signal pathway in ALI and will also prove new clues for ALI treatment.

急性肺损伤（Acute lung injury，ALI）死亡率仍居高不下。我们既往发现ALI小鼠肺部RUNX1（runt-related transcription factor 1）表达下调；LPS诱导气道上皮细胞RUNX1定向敲除基因工程小鼠ALI死亡率高于对照，下调A549细胞RUNX1可促进LPS刺激该细胞表达炎症细胞因子，但机制不明。本项目拟观察ALI患者、LPS和盲肠结扎穿孔诱导ALI小鼠的气道上皮细胞RUNX1表达，通过气道上皮细胞RUNX1过表达/定向敲除基因工程小鼠和细胞模型，研究体内、体外上调或下调气道上皮细胞RUNX1表达对ALI中NFκB信号通路的影响及可能机制；探索腺病毒载体和定向基因调控技术上调气道上皮细胞RUNX1能否逆转ALI肺部炎症及机制。通过上述研究，可明确气道上皮细胞RUNX1通过NFκB信号通路调控ALI肺部炎症的机制，为ALI防治提供新线索。

本项目研究发现，RUNX1表达于胚胎、新生及成年小鼠肺的间充质和上皮细胞中。定向敲除气道上皮细胞RUNX1虽不影响胎鼠肺正常发育，但会加重LPS诱导的肺部炎症反应。上调RUNX1表达可抑制LPS诱导的小鼠肺部炎症反应。以上结果提示：RUNX1与NF-κB信号通路密切相关。体外机制研究发现，LPS和TNFα刺激A549细胞，可诱导RUNX1从细胞核转位至细胞浆，与NF-κB通路上游关键分子IKKβ相互结合形成复合物，进而抑制NF-κB活化。上述研究结果表明，肺部定向敲除RUNX1可通过促进LPS诱导的NF-κB信号通路活化加重肺部炎症反应。本项目研究为呼吸道上皮细胞中RUNX1表达与ARDS之间的关系提供了理论依据，并说明在ALI/ARDS发病过程中维持呼吸道上皮细胞中RUNX1的表达水平的重要性。