VEGF调控体外循环相关肺炎性反应进程的机制研究

Our pilot studies suggest that Lung Inflammatory Response (LIR) may be under the control of Vascular Endothelial Growth Factor (VEGF) via its receptors during the Extracorporeal Circulation (ECC). Lower concentration of VEGF, during the early LIR, may facilitate the inflammation by promoting the release of pro-inflammatory cytokine; while during the latter LIR, higher level of VEGF enhances the release of anti-inflammatory cytokines, which induces the balance towards to anti-inflammation. Using rat ECC model, the aim of this project, therefore, is to observe the VEGF signal system changes during the LIR process induced by ECC, and the effects of VEGF signal system on LIR progress. Then using cell culture model in vitro, we study the effects of different concentrations of VEGF on the inflammatory cytokine release of pulmonary mononuclear cells, and the regulatory mechanism of VEGF on cytokine release via gene silencing the receptors of VEGF respectively. At last, using gene silencing model on rat, we test the hypothesis that LIR process can be changed by controlling VEGF receptors, which may reduce acute lung injury (ALI) induced by ECC..LIR-mediated ALI is still the leading cause of death in patients undergoing ECC. Because of short of the effective therapy currently, the research with regarding to the regulatory mechanism of LIR becomes most important for us to inhibit the development of ALI. This project provides a theoretical and experimental basis for understanding ALI pathogenesis and pathological processes in-depth, so as for the development of the potential drugs and monitor indexes to early diagnosis and treatment, which may result in significant improvement of the prognosis of ALI induced by ECC.

我们的前期研究发现，体外循环（ECC）中血管内皮生长因子（VEGF）可能通过不同受体控制着肺炎性反应（LIR）进程：炎性早期VEGF对LIR产生许诺作用，而后期则通过促进抑炎因子释放而抑制LIR。本项目拟使用在体ECC模型，研究VEGF系统在LIR进程中的变化，以及VEGF信号系统对LIR进程的控制作用；使用离体细胞培养模型，研究VEGF对肺单个核细胞炎性相关细胞因子的调控作用；利用基因沉默技术，分别/联合沉默VEGF的不同受体，研究VEGF对LIR的调控机制；并通过基因沉默ECC模型，研究通过控制VEGF受体是否能够改变LIR进程，减轻急性肺损伤（ALI）。.LIR介导的ALI仍是ECC后患者死亡的主要原因。由于缺乏有效治疗手段，探索LIR的调控机制为深入了解ALI发病机制和病理过程，并为开发特效药物和治疗手段，从而减轻ALI、改善患者预后提供理论和实验依据。

我们的临床和动物实验均发现，体外循环（ECC）后血浆血管内皮生长因子（VEGF）显著下降，但在肺组织中显著增加。静脉或气道内给予VEGF能进一步增加其肺浓度，抑制肺炎症反应，改善ECC后呼吸功能。这种作用可被抗VEGF抗体所拮抗。然而离体实验显示，VEGF并不能直接抑制肺单核巨噬细胞炎性因子的释放。.VEGF能诱导干细胞归巢。随后我们的实验显示，给予VEGF能显著增加肺组织CD133+干细胞数量，这些干细胞位于肺单核巨噬细胞附近。体外实验证实，CD133+干细胞能显著抑制肺单核巨噬细胞释放炎性因子。在体实验也证实，静脉内给予CD133+细胞，或使用G-CSF预动员均能够显著增加肺组织干细胞数量，抑制肺炎症反应，改善呼吸功能。这些结果提示：肺炎症过程中，循环VEGF能迅速进入肺组织，并诱导循环内CD133+干细胞归巢，归巢的细胞抑制肺单核巨噬细胞分泌炎症因子，从而减轻肺炎症反应。.呼吸道与外界相连，肺组织内富含免疫细胞，以清除入侵的异物、细菌、病毒，但这一特点也使其成为炎性反应中最易受损的器官之一。然而目前对肺炎症的调控机制依然知之甚少，使肺炎症损伤依然是造成患者死亡的主要原因。本研究提示，VEGF诱导的干细胞归巢是肺炎症调控的重要机制之一，这对于预防、治疗急性肺损伤可能具有极其重要的意义。