呼吸机相关性肺炎中HMGB1参与肺部炎症失控的机制研究

Patients suffered from ALI/ARDS are likely be receiving treatment of mechanical ventilation(MV),but prolonged mechanical ventilation(PMV) may cause lung inflammation uncontrollable,also known as nonresolving inflammation which characterized by repeated infection due and continued tissue damage.It was the main reason of the low cute rate and high motality of this kind of people in ICU,the definite mechanisms inside were unknown.Based on the relevant articles and fundamental work we have done,we suppose that HMGB1,working as a amplifying factor,may play a vital role in lung nonresolving inflammation.The underlying mechanism maybe that mechanical ventilation can activate TGF-β and HMGB1 together with TGF-βcan induce each other's generation,finally a large quantity releasing of HMGB1 can damage the tissue by amplifying the lung inflammation and cause the continued infection by impairing the ability of organism to denfense the 1`opportunistic pathogen,which directly affect the occurrence and development of lung nonresolving inflammation caused by ventilator assossiated pneumonia.Therefore,we plan to use cecal ligation and puncture model to induce the basal lung injury,then practise PMV tegether with bacterial infection,we intend to discuss how HMGB1 and its relevant signal path working on lung nonresolving inflammation via this model combined with clinical research.Our work can provide new evidence to illucidate the mechanism of lung nonresolving inflammation,moreover we can offer new strategy to resolve the issues of ALI/ARDS patients' lung nonresolving inflammation after receiving mechanical ventilation.

长时间机械通气(PMV) 治疗的重症患者肺部常发生反复感染和持续组织损伤（呼吸机相关性肺炎，VAP），易引起肺部炎症失控，是ICU中此类患者治愈率差和死亡率高的主要原因，具体机制尚未明确。根据文献报道及我们的工作基础，推测HMGB1（一种重要的损伤相关模式分子）在肺失控性炎症中发挥重要作用。具体机制可能为，机械通气活化TGF-β，TGF-β与HMGB1相互诱生，HMGB1的持续产生放大了肺部的炎症反应并造成组织损伤，同时削弱机体对细菌的防御力引起反复感染，这可能是VAP中肺部炎症失控的主要原因。据此，本课题拟以盲肠结扎穿孔模型诱导肺损伤，在此基础上行PMV合并细菌感染，通过此肺部非可控性炎症模型，并结合临床，探讨HMGB1及其相关信号通路参与肺部炎症失控的机制。通过本项目将为阐明肺部炎症失控机制提供新的依据，为解决ICU内ALI/ARDS患者机械通气后肺部失控性炎症问题提供新的策略。

本研究采用流式细胞仪和液相色谱、免疫荧光、分子生物化学、蛋白免疫印迹等手段，并运用在体和细胞水平的急性肺损伤和呼吸机肺损伤模型研究机体的炎症发生发展、消退以及炎症失控等变化，我们发现：.（1）急性肺损伤动物模型下机体内源性的RvD1表达规律；（2）消退素D1通过诱导AKT信号通路磷酸化抑制凋亡相关信号分子的表达减轻脂多糖诱导的人原代肺泡上皮细胞凋亡，以及通过抑制抑制人原代肺泡上皮二型细胞内 IκB-α 的降解和磷酸化从而起抗炎作用；（3）HMGB1和RIP3在重症肺炎中表达升高，并且坏死增多、凋亡减少，可能是肺部炎症失控的原因；（4）用盲肠结扎穿孔模型在第一天和第四天分别行小潮气量通气和中等潮气量通气，发现CLP 4day+LMV和CLP 4day+MMV相对于CLP 4day的小鼠肺部中性粒细胞的浸润增多，MMV比LMV通气更容易加重已受损肺部的炎症反应，这一现象在脓毒症晚期（CLP后4day）更显著，LMV在脓毒症晚期（CLP后4day）能显著促进炎症因子的合成；（5）在体动物脂多糖和机械通气双重打击模型下，长时间机械通气可明显激活JAK2/STAT1信号通路，抑制JAK2/STAT1信号通路能减轻动物整体的炎症反应，包括减轻肺组织病理损伤，降低肺泡灌洗液内促炎症反应炎症因子水平，同时肺内细胞的凋亡和自噬均减少；（6）以远程缺血预处理为干预在一项大样本单中心研究中发现STAT3与STAT5共同激活介导了ToF患儿心肌保护的作用。上述结果综合证明了机械通气在肺部基础炎症后期以及较大潮气量和较长时间的通气对机体的炎症放大作用更明显，HMGB1作为急性肺损伤和机械通气损伤的重要炎症介质，其在活化巨噬细胞、中性粒细胞等多种固有免疫细胞的同时参与了肺组织损伤和放大炎症反应，与RIP3介导的程序性坏死和凋亡自噬等存在多种联系；HMGB1上游信号通路之一的JAK/STAT信号通路可能成为调控HMGB1以及炎症转归的治疗靶点。