阿片肽通过TLR4/NF-κB改善感染性休克微循环障碍的机制研究

Septic shock, which developed rapidly and with a high mortality rate of 40%-50%, is one of the leading causes of death among surgical critically illed patients. The core pathophysiologic mechanism of the occurrence and development of septic shock is microcirculation disturbance, and nowadays there is no specific treatment. Our previous study have showed that opioid peptide can significantly reduce the inflammatory response induced by myocardial ischemia/reperfusion, and improve coronary microcirculation by TLR4/NF-κB signal pathway. A lot of literature datas have confirmed that TLR4 signaling pathway played a role in LPS-induced activation of NF-κB and have become a critical target of anti-inflammatory therapy of septic shock up to now. Then whether or not opioid peptide could alleviate the inflammation reaction and improve microcirculation induced by septic shock. What is the key mechanism pathway involved? There is no literature reported both domestic and overseas. Therefore, This research aim to discuss more about the molecular mechanism of TLR4/NF-κB pathway, and try to clarify the biological function of TLR4/NF-κB pathway in the process of improvement of microcirculatory disturbance by opioid peptide. These researches can expand the understanding of TLR4/NF-κB pathway. Furthermore, the expected results could provide valuable target and method in clinical treatment of septic shock, which have important theoretical and clinical significance.

感染性休克病情发展迅速，病死率高达40%-50%，是外科危重病人死亡的主要原因之一，其发生发展的病理生理核心是微循环障碍，目前尚无特效治疗方法。课题组前期研究发现阿片肽可通过调节TLR4/NF-κB通路显著减轻缺血/再灌注心肌的炎症反应，改善冠脉微循环。大量文献资料证实，TLR4信号转导通路介导了LPS对NF-κB的活化，已成为目前感染性休克抗炎治疗的重要靶点。那么阿片肽是否通过TLR4/NF-κB通路纠治感染性休克炎症反应、改善微循环障碍？其中的关键机理是什么？目前国内外文献尚无报道。因此，本课题拟在前期研究基础上，深入探讨阿片肽调控TLR4/NF-κB通路的分子机制；阐明TLR4/NF-κB通路在阿片肽改善感染性休克微循环障碍中的功能意义。这些研究可以拓展对TLR4/NF-κB通路的认识，还可发现感染性休克临床治疗的新靶点和新方法，具有重要的理论和临床意义。

感染性休克（脓毒症）是ICU患者最重要的死亡原因。早期目标导向治疗虽能改善部分患者预后，但其病死率仍居高不下。本课题基于前期缺血/再灌注的研究启发，采用盲肠结扎穿孔法（CLP）构建感染性休克大鼠模型。并在模型动物的基础上，深入探讨U50488H（κ-阿片受体激动剂）对感染性休克大鼠血流动力学、细胞灌注、炎症因子、血清酶学、重要脏器形态及功能，以及关键分子蛋白TLR4、MyD88、IKKβ、IκBα、NF-κB p65表达等的影响。实验结果显示，U50488H能够显著减轻感染性休克后的血压降低、改善左心室舒缩功能、降低血乳酸水平、缓解中性粒细胞比例升高、降低炎症因子（TNF-α、IL-1β、IL-6和VCAM）水平、缓解血清白蛋白下降、减轻重要脏器（心、肺、肝、肾）的功能损伤、抑制心和肺TLR4、MyD88、IKKβ及NF-κB p65的蛋白表达、升高IκBα的蛋白表达。以上结果提示，阿片肽（U50488H）可能通过TLR4/MyD88/IKKβ/NF-κB通路，抑制TLR4、MyD88、IKKβ（磷酸化）的表达，促进IκBα磷酸化降解，上调NF-κB p65的表达，进而减轻感染性休克炎症因子TNF-α、IL-1β、IL-6等产生，从而发挥对心、肺、肝、肾等重要器官保护作用。本课题的研究成果拓展了对TLR4/NF-κB通路的认识，也提出了TLR4/MyD88/IKKβ/NF-κB通路在感染性休克治疗中的潜在价值，具有重要理论和临床意义。