血管过氧化物酶1通过调节一氧化氮代谢参与肺动脉高压的发病机制研究

Pulmonary arterial hypertension（PAH） is closely associated with the reduced level of nitric oxide (NO). The mechanisms underlying the reduction of NO in PAH are not fully understood. In addition to the decreased NO synthesis, there might be a marked increases of NO metabolism in PAH. Mammalian peroxidases plays a key role in the NO metabolism. Recently, we identified a novel peroxidase, vascular peroxidase 1 (VPO1), which is highly expressed in endothelial cells and smooth muscle cells of vascular tissue. Our preliminary data suggest that VPO1 might be an enzyme for NO metabolism, and the levels of VPO1 are increased in both the plasma of PAH patients and the pulmonary vascular tissue of PAH rats. In this project, we hypothesize that the up-regulation of VPO1 in the pulmonary vascular tissue is critical for the reduction of NO, which is the primary mechanism for the pathogenesis and development of PAH. We will test this hypothesis through a series in vivo and in vitro approaches. First, we will analyze the correlation of VPO1 and NO levels with pulmonary arterial pressure in PAH patients and hypoxia or monocrotaline-treated rats; Second, we will confirm the role of VPO1 in NO metabolism by employing in vitro biochemical experiments; Third, we will verify the role of VPO1 in PAH and NO metabolism using knock-out and transgenic animals. This project will provide mechanistic insights on the pathogenesis of PAH and possible targets for the therapy of PAH.

内源性一氧化氮（NO）水平降低与肺动脉高压（PAH）的发生发展密切相关。除生成减少外，代谢增加也是导致NO水平降低的重要原因，但其具体机制及其在PAH中的作用仍不清楚。血管过氧化物酶1（VPO1）是新近确定在血管组织中丰富表达的过氧化物酶，我们的前期研究发现VPO1不仅具有代谢NO能力，且其水平在PAH患者血浆及PAH大鼠肺血管组织中皆明显升高，因此我们推测VPO1可能通过调节NO代谢，降低内源性NO水平从而在PAH的发病中起着重要作用。本项目将在临床及动物研究揭示VPO1参与PAH发病的基础上，从生化、细胞、离体及在体四个层面，结合基因技术及工具药物证实VPO1是机体内调节NO代谢的重要途径。最后通过基因敲除及转基因动物确证VPO1介导PAH的发生与其调节NO代谢有关。本项目将从新的角度认识内源性活性物质NO参与PAH发病过程中的调节机制，为寻找新的药物作用靶点提供实验依据和理论支持。

氧化应激介导了肺动脉高压(PAH)的发生发展，VPO1是本课题组证实高表达于血管组织中的过氧化物酶家族成员，能催化H2O2(弱氧化剂)产生次卤酸(强氧化剂)从而诱导氧化应激。本项目从动物、细胞水平，结合基因沉默技术和工具药对VPO1与PAH的关系进行了深入系统的研究。主要发现包括：1）VPO1通过NOX4/VPO1/HOCl/NF-κB通路促进了低氧诱导的肺动脉平滑肌细胞增殖，凋亡抵抗和迁移，从而促进PAH的发生发展；2）VPO1通过促进HIF-1α的表达从而介导肺血管成纤维细胞分化及迁移；3）在培养的人脐静脉内皮细胞中，VPO1可通过PRMT1/AMDA通路调节eNOS表达，降低NO水平；4）在腹主动脉瘤患者与小鼠模型中VPO1水平升高，细胞实验发现VPO1可通过H2O2/VPO1/HOCl/ERK/KLF4信号通路调控血管平滑肌细胞的表型转化。这些发现对于确定VPO1介导的氧化应激在肺动脉高压中的作用，及VPO1与内源性活性物质NO的关系具有重要意义，同时为寻找PAH的干预靶点提供了理论依据。