创伤后巨噬细胞12/15LOX-12(S)HETE轴过度活化的分子机制及逆转措施研究

Macrophage dysfunction after trauma mediates susceptibility to infection, leading to high incidence of infection especially sepsis. 12/15-LOX and its metabolite 12(S)-HETE play an important role in regulating the function of macrophage. Our previous studies found that 12/15-LOX and 12(S)-HETE were significantly increased in macrophage of traumatic mice, and the latter was associated with the prognosis of sepsis. And 12/15-LOX inhibitors had protective effect on infected mice after trauma. Then we proposed the following scientific hypothesis, 12/15-LOX and 12(S)-HETE are over-activated in traumatic macrophage which mediated dysfunction. The project intends to clarify the following problems: ①the upstream transcription factor of 12/15-LOX, ②the downstream receptor of 12(S)-HETE and how it influences the function of macrophage including the secretion of pro-inflammatory and anti-inflammatory factors, and the polarization of M1 and M2, ③whether regulating the expression of 12/15-LOX and 12(S)-HETE can reverse dysfunction of macrophage, ④Is the combination of the above measure and antibiotic therapy effective on post-traumatic infection in vivo? This study is not only helpful to reveal the new mechanism of dysfunction in macrophage after trauma, but also to explore new measures to reverse immune dysfunction after trauma.

严重创伤后巨噬细胞（Mφ）功能紊乱介导了机体对感染的易感性，导致伤后感染及脓毒症的发生率居高不下。近来研究证实，12/15-LOX及其代谢产物12(S)-HETE对Mφ功能具有重要调控作用。我们前期发现“创伤小鼠Mφ 的12/15-LOX和12(S)-HETE显著升高，且后者与脓毒症不良预后相关，而应用12/15-LOX抑制剂对创伤感染小鼠具有生存保护作用”，进而提出科学假设：创伤后Mφ 12/15LOX-12(S)HETE轴的过度活化介导了Mφ功能紊乱。本项目拟明确：①创伤后调节Mφ 12/15-LOX表达的转录因子；②12(S)-HETE通过何种受体介导Mφ促炎/抗炎因子分泌及M1/M2极化；③调节该轴可否逆转Mφ功能障碍；④体内应用上述调节措施及联合抗生素治疗对创伤后机体抗感染的协同效应。该研究不仅有助于揭示创伤后Mφ功能紊乱的新机制，而且有助于发掘逆转创伤后免疫功能紊乱的新措施。

严重创伤后由感染引发的并发症是阻碍危重症患者救治成功率的主要瓶颈。本课题围绕“严重创伤后机体更易感”的科学问题展开，基于“严重创伤后巨噬细胞12/15LOX-12(S)HETE轴过度活化的正反馈环”假说，从轴的上下游，轴的效应，轴的调控三方面进行研究，已证实：①小鼠严重创伤后血清中12(S)HETE浓度增加，后者通过其受体Gpr31上调巨噬细胞12/15LOX表达，在高浓度花生四烯酸（感染后血清中浓度显著增加）作用下，活化的12/15LOX代谢花生四烯酸生成更多的12(S)HETE（正反馈轴）。②严重创伤后巨噬细胞该轴的过度活化导致其在花生四烯酸作用下易发生铁死亡（轴效应）；另外，大量12(S)HETE也可通过抑制NO生成促进细胞铁死亡。③以12/15LOX为靶点的黄芩苷胶囊（轴调控）通过抑制该正反馈环路的活化提高机体伤后抗感染能力，尤其是联合抗生素效果优于单独抗生素组。综上，该课题阐明了“严重创伤后巨噬细胞的过度活化导致其在感染因素下更易发生铁死亡，从而降低了机体抗感染能力”，这为临床开展伤后抗感染的防治措施提供了理论支持和实验依据。