急性肺损伤时局部ACE2-Ang1-7-Mas受体轴的调控作用及其信号转导机制

Acute lung injury (ALI) is a devastating disorder of overwhelming pulmonary inflammation leading to hypoxaemia and respiratory failure, for which there is no effective therapeutic option in most of the cases. Previously, Angiotensin-converting enzyme (ACE) and its effector peptide angiotensin (Ang) II have been implicated in the pathogenesis of ALI. In recent years, ACE2, A counter-regulatory enzyme of ACE, that degrades Ang II to Ang-(1-7), offers a promising novel treatment modality for ALI. Our preliminary study suggested that Angiotensin-converting enzyme inhibitor (ACEI) can significantly attenuate the ALI induced by LPS in rat, and may be associated with the local regulation of ACE2, but its mechanism remains to be further explored. After learning from many literatures, we hypothesize that the regulation of local ACE2-Ang1-7-Mas axis, especially ACE2, may inhibit local inflammatory response and attenuate acute lung injury through the mitogen-activated protein kinases (MAPKs) signal pathways. To test this hypothesis, we will use the Lentiviral packaged ACE2-cDNA or ACE2-shDNA to transfect the rat pulmonary micro-vascular endothelial cells and SD rats, then detect the changes of local ACE2-Ang1-7-Mas axis and its relationship with the MAPKs pathways during LPS induced acute lung injury by the means of western-blot, real-time PCR, HPLC mass spectrometry et al. Finally, after exploring in all aspects including molecular, cellular, tissues and the overall level of animal, we will determine the role of regulating local ACE2-Ang1-7-Mas axis and the trans-membrane signaling properties of ACE2 through the intracellular signal transduction of MAPKs pathways in acute lung injury. The purpose of this study is to identify the effect of local ACE2-Ang1-7-Mas axis during LPS induced acute lung injury and its corresponding intracellular signal pathways. From the results of this study, a novel effective therapeutic methods for ALI based on the regulation of local ACE2 may be developed.

急性肺损伤（ALI）缺乏有效治疗手段，死亡率高。ACE2作为新的潜在有效治疗手段得到越来越多学者的重视。我们的前期实验结果提示ACEI可明显减轻LPS导致的大鼠ALI，并与局部ACE2调控有关，但作用机制还有待探讨。结合文献我们提出假设：局部ACE2-Ang1-7-Mas轴可能通过MAPKs信号通路发挥抑制炎症反应并减轻ALI的作用。为验证这一假说，我们将通过大鼠原代肺微血管内皮和ALI模型，应用慢病毒转染ACE2-cDNA/shRNA，采用western-blot、RT-PCR、高效液相质谱分析等手段，从分子、细胞、组织及动物整体等多方面探讨局部ACE2-Ang1-7-Mas轴在ALI时的调控，明确其通过MAPKs通路进行细胞内信号转导的机制。本研究旨在阐明局部ACE2-Ang1-7-Mas轴在急性肺损伤时的调控作用及其机制，为通过ACE2途径治疗ALI奠定基础并提供新的思路。

急性呼吸窘迫综合征（Acute Respiratory Distress Syndrome, ARDS）是一种以急性呼吸衰竭及严重低氧血症为特征的危重疾病。目前尚缺乏有效治疗手段，死亡率高。脓毒症是引起ARDS最常见的病因。LPS是导致严重脓毒症的始发因素。近年来的研究显示，肾素-血管紧张素系统（renin-angiotensin system, RAS）可能在ARDS 的发生发展中起重要作用；然而，具体调控机制尚未阐明。因此，我们探讨在LPS 导致急性肺损伤过程中，调控局部ACE/ACE2 的表达对肺损伤的影响及相关信号通路的作用。ACEI 预处理可能通过调节局部ACE/ACE2 表达平衡及抑制MAPKs 信号通路活化，发挥对LPS 所致急性肺损伤及PMVECs 细胞毒性的保护作用。上调ACE2 表达可在肺损伤过程中发挥保护作用，其作用机制主要是通过Ang1-7/Mas 受体途径，并抑制MAPKs/NF-κB 信号通路激活。我们的研究证实调节或恢复局部ACE/ACE2 表达平衡可能是防治ARDS 的潜在而有效的治疗途径。