HO-1/自噬流反馈环路在脓毒症小鼠肺损伤中的作用和机制研究

Lung is a common vulnerable organ in sepsis, and inhibition of inflammation cascade is one of the keys to prevent and treat the septic lung injury. Heme oxygenase-1 (HO-1) could alleviate the inflammatory response, play a protective role in organism response, but the underlying mechanisms of it has not been completely clear. Our preliminary data showed that HO-1 inducer Hemin attenuates lung injury of septic mice, inhibits inflammasome activation and promotes autophagic flux. Meanwhile, autophagic flux receptor P62 is reported to regulate the transcription of HO-1. Thus we infer that HO-1 promoted autophagic flux, and inhibition of autophagic flux could induce HO-1 transcriptional expression, which formed a feedback loop between HO-1 and autophagic flux, and regulated inflammatory cascade and lung injury in sepsis. In this study, we first detect the HO-1 and autophagy flux in lung tissue of septic mice to confirm the correlation between them. Then, we’ll use intervention agents or lentiviral vector technology to clarify that HO-1 participates in the process of inflammasome activation by regulating autophagy flux through CREB signal pathway. Finally, we will verify the role of autophagic flux and P62/NRF2 in HO-1 transcription and expression. All these are expected to reveal the effect and mechanisms of HO-1/autophagic flux feedback loop in lung injury of sepsis, and this will show a novel evidence and foundation for the treatment of septic lung injury.

肺脏是脓毒症常易累及的脏器，抑制炎症级联反应是防治脓毒症肺损伤的关键之一。HO-1能减轻炎症反应，在机体应答中起保护作用，但具体机制尚未完全清楚。前期研究显示：HO-1诱导剂Hemin可减轻脓毒症肺损伤、抑制炎症小体活化、促进自噬流；而自噬流关键受体P62被报告能调节HO-1转录。由此，我们推测HO-1促进自噬流，而自噬流受阻可诱导HO-1的转录表达，二者形成反馈环路调控脓毒症肺损伤炎症级联。在本研究中，我们选用Balb/c小鼠和原代肺泡巨噬细胞为研究对象，首先检测脓毒症HO-1表达和自噬流情况，确定二者的相关性；再利用干预剂或慢病毒载体技术调节HO-1，阐明HO-1通过CREB调控自噬流，影响炎症小体活化；最后利用干预剂调节自噬流，明确自噬流通过P62/NRF2调控HO-1的转录表达。本研究旨在揭示HO-1/自噬流反馈环路在脓毒症肺损伤中的作用及调控机制，为治疗脓毒症提供新的思路和证据。

脓毒症是由感染引起的机体生理、生化、病理异常综合征，导致器官功能障碍，危及患者生命，是重症监护病房患者最严重的并发症及致死原因，病死率高达30-50%，而肺脏是脓毒症最易累及的脏器之一，阐明其发生机制，寻找新的有效防治措施，具有重要的基础和临床意义。本研究构建脓毒症小鼠模型，检测肺损伤、炎症小体、HO-1表达水平和自噬情况，并分别调控HO-1和自噬，探索HO-1和自噬对脓毒症小鼠肺损伤的调控，以及HO-1与自噬间的分子对话。研究结果显示：①脓毒症小鼠存在肺损伤、炎症小体活化、HO-1过表达和自噬流的受阻；②HO-1能减轻脓毒症小鼠肺损伤和炎症小体活化程度，促进自噬流；③自噬能减轻脓毒症小鼠肺损伤和炎症小体活化程度，诱导HO-1表达。以上研究揭示HO-1/自噬流在脓毒症肺损伤和炎症小体活化中的调控作用及其机制，为脓毒症的防治提供新思路与实验依据。