炎症消退障碍所致失控性炎症是ALI重要发病机制。脂氧素A4(LXA4)是机体重要内源性抗炎促消退介质。我们发现在炎症过程中COX-2呈双峰表达，且NF-κB p50/p50介导COX-2第二峰；LXA4双向调控COX-2双峰，通过抑制COX-2第一峰和PGE2表达限制炎症反应，并上调COX-2第二峰和PGD2水平促进炎症消退。据此，我们提出假说：LXA4可能通过调控NF-κB p50/p50上调COX-2第二峰的促炎症消退作用,发挥肺保护功能。本项目拟采用内毒素性ALI细胞和动物模型，应用UPLC-MS、凝胶迁移率、ChIP、双荧光素酶报告基因、基因过表达、基因敲除等方法，①明确LXA4、COX-2在ALI发生发展中的作用；②验证COX-2第二峰介导LXA4肺保护作用；③揭示LXA4调控NF-κB p50/p50上调COX-2第二峰的具体分子机制。为ALI防治策略提供新思路。

The excessive inflammation caused by a failure of resolution is the fundamental pathophysiology of ALI. Lipoxin A4 (LXA4) is an important endogenous specialized pro-resolving mediator, which orchestrates inflammatory resolution. Our previous study illustrated that there was a biphasic cyclooxygenase-2(COX-2) activation pattern in the progress of inflammation, NF-κB p50/p50 was shown to be responsible for the second peak of COX-2. In addition, LXA4 could exert an anti-inflammatory effect by inhibiting the first COX-2 peak and PGE2 production in the proinflammatory phase, whereas act pro-resolving function by increasing the second COX-2 peak and PGD2 level during the resolution phase. Therefore, we hypothesized that LXA4 might activate NF-κB p50/p50 homodimers, dominate the second COX-2 peak to expedite the resolution of inflammation. The methods of UPLC-MS, EMSA-supershift, ChIP, laser confocal, dual-luciferase report gene as well as gene over-expression, gene knockout technology will be used to validate this hypothesis. Firstly, we will confirm the roles of LXA4 and COX-2 act in the development of ALI.Secondly, we will clarify that the second COX-2 peak is responsible for the protective role of LXA4 in ALI. Lastly, we will identify the molecular mechanism of LXA4 modulating NF-κB p50/p50 to activate pro-resolving COX-2 expression. The information derived from this study will not only elucidate the cellular and molecular mechanisms of LXA4 regulating the second COX-2 peak to promote resolution of inflammation, but also provide the proof-of-principle evidence for the novel prevention and treatment of ALI.