鸟苷解离抑制因子-2(Ly-GDI)在免疫复合物诱导的急性肺损伤中的作用及其机制的研究

Since the pathophysiological mechanisms are unclear, patients with acute lung injury and its severe form, acute respiratory distress syndrome, still have a very high mortality rate. Growing evidences demonstrate that IgG immune complexes and their receptors play an important role in the initiation and development of acute lung injury and acute respiratory distress syndrome. However, its molecular basis and the underlying regulatory mechanisms remain to be determined. Ly-GDI is an inhibitory protein of Rho GTPases. Although Ly-GDI plays an essential role in regulating actin cytoskeletal alteration which is indispensible for the process such as phagocytosis, the role of Ly-GDI in inflammation is unknown. The results of our preliminary experiments suggest that Ly-GDI may play an important regulatory role in IgG immune complex-induced lung injury. Thus, this study will use IgG immune complex-induced lung injury model in the mouse to illucidate the function of Ly-GDI in acute lung injury and its cellular and molecular mechanisms. Simutaneously, we will explore the regulatory effects of IgG immune complexes on Ly-GDI expression in the lung and alveolar macrophages as well as the mechanisms.

由于病理生理机制不完全清楚，急性肺损伤及其严重形式急性呼吸窘迫综合征患者的死亡率仍居高不下。越来越多的证据显示IgG免疫复合物及其受体在急性肺损伤及急性呼吸窘迫综合征的发生发展过程中起着重要的作用。但其分子机制仍有待明确。鸟苷解离抑制因子-2 (Ly-GDI)是Rho GTP酶抑制蛋白。虽然Ly-GDI在调控吞噬过程所必需的肌动蛋白细胞骨架改变中发挥着重要作用，其在炎症中的作用尚属未知。我们的前期实验结果表明Ly-GDI可能对IgG免疫复合物引起的肺损伤有重要调节作用。因此，本研究将利用IgG免疫复合物诱导的小鼠肺损伤模型阐明Ly-GDI在急性肺损伤中的功能及其细胞分子生物学机制。同时我们还将探索IgG免疫复合物对Ly-GDI在肺组织和肺泡巨噬细胞中表达的调控及其机制。

为了阐明鸟苷酸解离抑制因子（Ly-GDI）在IgG免疫复合物引起的急性肺损伤中的调控作用和机制，我们通过体外干扰肺泡巨噬细胞系（MH-S）中的Ly-GDI和利用腺病毒载体在IgG 免疫复合物诱导的急性肺损伤模型中过表达Ly-GDI的方法，验证了Ly-GDI在上述病理炎症反应中的负调控作用。此外，为了研究IgG免疫复合物影响Ly-GDI表达的分子机制以及在转录水平上的调控机制，我们对不同长度的Ly-GDI启动子转录活性进行分析，并预估了可能发挥重要作用的转录因子。重要的研究结果显示：Ly-GDI可以通过调控C5a 受体和FcγRs及其下游激酶蛋白的表达从而减轻肺泡巨噬细胞的炎症反应；Ly-GDI能够显著降低急性肺损伤中的验证反应；Ly-GDI表达有可能受以下转录因子的调控（Oct-2.1、Oct-2.3、Oct-2.4、Oct-2.6、C/EBP α）。以上研究工作为通过Ly-GDI缓解急性肺损伤和急性呼吸窘迫综合征提供了分子水平的理论依据；为进一步探讨Ly-GDI在急性肺损伤模型中表达变化的分子机制打下了重要的基础。