Identification of the superoxide source of tobacco-smoke-induced emphysema and pulmonary hypertension, pathogenesis and regeneration.

慢性阻塞性肺疾病（COPD）是一种发病率不断上升的主要疾病。预计到2030年，它将在全球最常见的死亡原因中排名第三。这种迄今无法治愈的疾病的主要诱因是吸入烟草和空气污染。尽管高达70%的COPD患者患有肺动脉高压（pulmonary hypertension， PH），但其对COPD发病机制的影响尚不清楚。最近的一项假说甚至认为血管的改变会引发肺气肿的发展。在这方面，我们最近在小鼠模型中表明PH先于肺气肿的发展，应用的小鼠模型很好地反映了人类疾病的时间进程。我们的研究发现，诱导型NO合成酶（iNOS）是烟雾诱导肺气肿和PH发展的关键酶：敲除小鼠的iNOS基因可以完全保护疾病。此外，药理抑制iNOS不仅可以阻止PH和肺气肿的发展，甚至可以逆转已建立的肺气肿和PH，从而导致肺再生（Seimetz et al., Cell, 2011）。基于我们的研究结果的病理生理学概念认为，过氧亚硝酸盐是由NO（由血管iNOS产生）与超氧化物反应形成的，是肺气肿和PH发展的关键介质。虽然一氧化氮的来源已经确定，但产生超氧化物的系统仍然是未知的。根据这一建议，我们将重点关注超氧化物源及其信号传导。在之前的筛选中，我们已经确定了NADPH氧化酶（NOX）异构体作为潜在的超氧化物来源。在疾病发展的整个过程中，暴露于烟草烟雾的小鼠的肺泡和血管室中，细胞质亚基NOX组织者1 （NOXO1）是唯一上调的NOX亚基。在我们对人类COPD肺的研究中发现了类似的调节。在此背景下，我们已经生成了带绒的NOXO1小鼠。因此，根据目前的建议，我们的目标是：(1)确定NOXO1依赖性超氧化物形成在肺气肿和PH的发病机制中的详细作用；(2)NOXO1及其信号传导作为再生肺气肿和PH治疗靶点的适用性。此外，计划实验的目的是鉴定负责肺气肿和PH发展的细胞类型。在这方面，我们的概念假定了在血管室中产生超氧化物的细胞的重要作用。通过对COPD患者肺样本的平行研究，我们研究的总体目标是确定预防和再生肺气肿肺的新策略。

Chronic obstructive pulmonary disease (COPD) is a major disease with ever increasing incidence. It is predicted to be ranked third place of the most frequent causes of death worldwide in 2030. Major triggers of this hitherto incurable disease are inhalative tobacco-smoking and air pollution. Although up to 70% of COPD patients suffer from pulmonary hypertension (PH) its impact on the COPD pathogenesis is not uncovered yet. A recent hypothesis even postulated that vascular alterations can trigger emphysema development. In this regard we recently showed in a mouse model that PH precedes emphysema development, with the applied mouse model quite well reflecting the time course of the human disease. Our investigations identified the inducible NO synthase (iNOS) as key enzyme for the development of smoke-induced lung emphysema and PH: A knockout of the iNOS gene in mice resulted in complete protection from the disease. Moreover, a pharmacological iNOS inhibition could not only prevent PH and emphysema development, but even reversed established emphysema and PH and thus led to lung regeneration (Seimetz et al., Cell, 2011). The pathophysiological concept based on our results claimed peroxynitrite, formed by the reaction of NO (generated by a vascular iNOS) with superoxide, as a key mediator of emphysema and PH development. While the NO source was identified, the superoxide-generating system is still unknown. With this proposal we thus will focus on the superoxide source and its signaling. In a preceding screening, we could already identify an NADPH oxidase (NOX) isoform as a potential superoxide source. The cytosolic subunit NOX organizer 1 (NOXO1) was the only NOX subunit upregulated in the alveolar and vascular compartment in tobacco smoke-exposed mice during the entire time course of the disease development. An analogous regulation was found in our investigations in human COPD lungs. Against this background we have already generated floxed NOXO1 mice. Thus, with the current proposal we aim i) to identify the detailed role of the NOXO1-dependent superoxide formation for the pathogenesis of lung emphysema and PH and ii) the suitability of NOXO1 and its signaling as a target for regenerative emphysema and PH therapy. Furthermore, the aim of the planned experiments is the identification of the cell types being responsible for emphysema and PH development. In this regard our concept postulates an essential role of superoxide-producing cells in the vascular compartment. With parallel investigation in human lung samples from patients with COPD the overall aim of our study is to identify new strategies not only for prevention but also for regeneration of emphysematous lungs.