Nitric Oxide Regulation of Compensatory Lung Growth

全肺切除(全肺切除)对于无法治愈的患者来说是一种挽救生命的程序；但它会带来相当大的发病率和死亡率。虽然肺切除会导致剩余肺的快速生长，但这种代偿性肺生长(CLG)的刺激因素和分子机制仍不清楚。了解这些机制将回答有关CLG和器官再生的重要问题。因此，这项提议的长期目标是了解触发和调节CLG的分子介体。一氧化氮(NO)是CLG的重要调节因子，在内皮细胞和II型肺泡细胞中介导关键生长因子的血管生成和有丝分裂特性。因此，这一提议将检验总的假设，即NO是通过调节血管生成和II型细胞增殖来调节CLG的关键介质。为了验证这一假说，将利用内皮型一氧化氮合酶(ENOS)、诱导型一氧化氮合酶(INOS)以及eNOS/iNOS两种基因敲除缺陷的小鼠来研究肺切除术后CLG的NO介导机制。具体目标1将通过调节血管生成和II型细胞的增殖和分化来检验CLG需要NO的假设。将在一氧化氮合酶缺陷小鼠中测量血管生成和II型细胞的增殖和分化。《特定目标2》将通过调节肺组织中特定增殖因子的表达来验证NO对慢性萎缩性胃炎必不可少的假说。检测细胞因子、一氧化氮合酶、生长因子及其受体的表达。CLG的增强作用将通过给予外源生长因子进行测试，吸入NO的使用将决定NO对CLG至关重要的时间。特异靶3将验证NO调节CLG的机制是通过cGMP信号通路和MAPK级联反应的假说。CGMP依赖的激酶I和MAPK的激活将被检测，在使用选择性药物抑制剂抑制cGMP依赖的激酶I后，将在小鼠中检测CLG。识别再生肺生长中的分子介质不仅将推动肺生物学和移植领域的发展，而且将通过刺激和控制肺生长和再生来促进肺损伤和终末期肺部疾病的未来治疗。

Pneumonectomy (removal of a whole lung) is a life-saving procedure in patients who cannot otherwise be cured; but it carries considerable morbidity and mortality. While pneumonectomy results in rapid growth of the remaining lung, the stimuli and molecular mechanisms of this compensatory lung growth (CLG) remain unknown. Understanding these mechanisms will answer important questions concerning CLG and organ regeneration. Thus the long-term objectives of this proposal are to understand the molecular mediators that trigger and regulate CLG. Nitric oxide (NO) is an important regulator of CLG, and is known to mediate the angiogenic and mitogenic properties of key growth factors in endothelial cells and type II alveolar cells. Thus this proposal will test the overall hypothesis that NO is a key mediator of CLG through the modulation of angiogenesis and type II cell proliferation. To test this hypothesis, knockout mice deficient in endothelial NO synthase (eNOS), inducible NOS (iNOS), and both eNOS/iNOS will be used to study NO-mediated mechanisms of post-pneumonectomy CLG. Specific Aim 1 will test the hypothesis that NO is required for CLG by modulating angiogenesis and type II cell proliferation and differentiation. Angiogenesis and type II cell proliferation and differentiation will be measured in the NOS-deficient mice. Specific Aim 2 will test the hypothesis that NO is essential to CLG by modulating expression of specific proliferation factors in the lung. Expression of cytokines, NOS, growth factors and their receptors will be measured. Augmentation of CLG will be tested by administration of exogenous growth factors, and use of inhaled NO will determine the times during which NO is critical to CLG. Specific Aim 3 will test the hypothesis that a mechanism of NO- regulated CLG is via the cGMP signaling pathway and the MAPK cascade. Activation of cGMP-dependent kinase I and MAPK kinase will be determined, and CLG will be measured in mice after the inhibition of cGMP-dependent kinase I using a selective pharmacologic inhibitor. Identification of the molecular mediators in regenerative lung growth will not only advance the field of lung biology and transplantation, but will permit the advancement of future therapies for lung injury and end-stage lung disease through the stimulation and control of lung growth and regeneration.