Nitric Oxide Regulation of Compensatory Lung Growth

全肺切除术（切除整个肺）是一种挽救无法治愈的患者生命的手术；但它有相当高的发病率和死亡率。虽然全肺切除术导致剩余肺的快速生长，但这种代偿性肺生长（CLG）的刺激和分子机制尚不清楚。了解这些机制将回答有关CLG和器官再生的重要问题。因此，本提案的长期目标是了解触发和调节CLG的分子介质。一氧化氮（NO）是CLG的重要调节因子，并介导内皮细胞和II型肺泡细胞中关键生长因子的血管生成和有丝分裂特性。因此，本研究将验证一氧化氮通过调节血管生成和II型细胞增殖是CLG的关键介质的总体假设。为了验证这一假设，将内皮NO合酶（eNOS）、诱导型NO合酶（iNOS）和eNOS/iNOS缺失的敲除小鼠用于研究NO介导的肺切除术后CLG机制。特异性目的1将通过调节血管生成和II型细胞增殖和分化来验证一氧化氮是CLG所必需的假设。将在nos缺陷小鼠中测量血管生成和II型细胞增殖和分化。特异性目标2将通过调节肺中特定增殖因子的表达来验证NO对CLG至关重要的假设。检测细胞因子、NOS、生长因子及其受体的表达。CLG的增加将通过施用外源性生长因子进行测试，吸入NO的使用将决定NO对CLG至关重要的时间。特异性目的3将验证NO调节CLG的机制是通过cGMP信号通路和MAPK级联的假设。将测定cgmp依赖性激酶I和MAPK激酶的活化，并在使用选择性药物抑制剂抑制cgmp依赖性激酶I后测量小鼠的CLG。识别再生肺生长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推进肺损伤和终末期肺病的未来治疗。

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.