Role of NLRX1 in cigarette smoke-induced pulmonary inflammation and remodeling

项目摘要 慢性阻塞性肺疾病（COPD）包括几种临床综合征，最值得注意的是 肺气肿和慢性支气管炎。它是人类健康中一个主要的未满足的医疗需求， 与香烟烟雾（CS）暴露有关。然而，目前的大多数治疗方法都不能减弱 疾病的严重程度和进展，因此需要更好地了解发病机制 来开发改善疾病的疗法。我们最近证明，核苷酸结合结构域和 富含亮氨酸重复序列的蛋白质X1（NLRX1）是一种新的线粒体分子， 在COPD发病机制中的抑制作用。NLXR 1的重要性在临床研究中也很明显。 从三个独立的人COPD队列中，NLRX 1的表达在肺中受到抑制， COPD患者和这种抑制表现出与气流受限程度的强相关性， 慢性阻塞性肺病的标志。目前的建议旨在界定制止恐怖主义的基本机制， NLRX 1的表达与COPD的发病机制有关，并确定NLRX 1的治疗潜力 体内恢复作为COPD的疾病改善剂。初步研究表明，（i）肺 巨噬细胞是NLRX 1在两种肺组织中表达最显著的细胞群， 非吸烟者和非吸烟（NS）对照小鼠;（ii）NLRX 1的表达在非吸烟小鼠和非吸烟（NS）对照小鼠中显著抑制。 来自暴露于CS的小鼠的肺巨噬细胞;和（iii）重要的是，CS-1的标记物的表达。 诱导活化的巨噬细胞（白细胞介素（IL）-18，线粒体活性氧（mtROS）， 与来自NLRX 1-/-小鼠的巨噬细胞相比，来自NLRX 1-/-小鼠的巨噬细胞中的金属蛋白酶（MMPs）显著增强。 来自CS暴露后的WT小鼠。这些结果突出了NLRX 1作为CS诱导的细胞凋亡的关键调节因子。 肺巨噬细胞的活化，这是一种在COPD发病机制中起主要作用的细胞群。 此外，我们发现NLRX 1与PTEN诱导的激酶1（PINK 1）相互作用，PINK 1是一种已知的 在线粒体质量控制（MQC）中具有重要作用。基于这些观察，我们假设 NLRX 1通过PINK 1作为CS诱导的肺巨噬细胞活化的关键抑制剂发挥作用- 介导的MQC。为了验证这一假设，我们将利用新产生的小鼠， 条件性NLRX 1-/-（M Φ-NLRX 1-/-）和巨噬细胞特异性NLRX 1转基因过表达（M Φ-NLRX 1 Tg）。目标如下：#1。表征CS对小鼠中NLRX 1表达的影响， COPD患者中NLRX 1表达的改变，并确定巨噬细胞特异性 NLRX 1在CS诱导的肺部炎症和重塑反应中的作用;#2。定义更改 暴露于CS的肺巨噬细胞的功能特征及其潜在机制 NLRX 1决定这些改变;#3。确定恢复体内NLRX 1表达是否改善 CS诱导的肺部炎症和重塑反应。

Project Summary Chronic obstructive pulmonary disease (COPD) encompasses several clinical syndromes, most notably emphysema and chronic bronchitis. It is a major unmet medical need in human health and is strongly associated with cigarette smoke (CS) exposure. Most of the current treatments, however, fail to attenuate severity and progression of the disease, thereby requiring better mechanistic understandings of pathogenesis to develop disease-modifying therapeutics. We recently demonstrated that the nucleotide-binding domain and leucine-rich-repeat-containing protein X1 (NLRX1), a novel mitochondrial molecule, plays an important inhibitory role in the pathogenesis of COPD. The importance of NLXR1 was also evident in clinical studies. From three independent human COPD cohorts, the expression of NLRX1 was suppressed in lungs from patients with COPD and this suppression showed strong correlation with the degree of airflow limitation, a hallmark of COPD. The current proposal aims to define the underlying mechanism(s) by which the suppression of NLRX1 contributes to the pathogenesis of COPD and to determine the therapeutic potential of NLRX1 restoration in vivo as a disease modifier of COPD. Preliminary studies revealed that (i) pulmonary macrophages were the cell population where the expression of NLRX1 was most prominent in lungs from both non-smokers and no-smoking (NS) control mice; (ii) the expression of NLRX1 was significantly suppressed in pulmonary macrophages from mice exposed to CS; and (iii) importantly, the expression of markers of CS- induced activated macrophages (interleukin (IL)-18, mitochondrial reactive oxygen species (mtROS), metalloproteases (MMPs)) were markedly enhanced in macrophages from NLRX1-/- mice compared to those from WT mice after CS exposure. These results highlight NLRX1 as a critical regulator of CS-induced activation of pulmonary macrophages, a cell population that plays a major role in COPD pathogenesis. Furthermore, we identified that NLRX1 interacts with PTEN-induced kinase 1 (PINK1), a molecule known to have an important role in mitochondrial quality control (MQC). Based on these observations, we hypothesize that NLRX1 plays as a critical inhibitor of CS-induced activation of pulmonary macrophages via PINK1- mediated MQC. To test the hypothesis, we will utilize newly generated mice that harbor macrophage-specific conditional NLRX1-/- (MΦ-NLRX1-/-) and macrophage-specific NLRX1 transgenic overexpression (MΦ-NLRX1 Tg). Proposed aims are as follows: #1. Characterize the effects of CS on the expression of NLRX1 in mice, the alteration of the expression of NLRX1 in patients with COPD, and define the role(s) of macrophage-specific NLRX1 in CS-induced pulmonary inflammation and remodeling responses; #2. Define the alteration of functional characteristics of CS-exposed pulmonary macrophages and the underlying mechanism(s) by which NLRX1 determines these alterations; #3. Determine if restoring the expression of NLRX1 in vivo ameliorates CS-induced pulmonary inflammatory and remodeling responses.