Mitochondrial Dysfunction and Metabolic Regulation of the Necroptosis Pathway in COPD and IPF

摘要 纤维化和肺气肿代表了慢性肺纤维化发病过程中出现的不同临床表型， 吸烟引起的肺部疾病（CS）。我们发现了独特的线粒体和代谢 对可能导致纤维化或肺气肿的发散性通路基础的有害刺激作出反应的通路 outcomesU.线粒体是调节代谢和能量产生的关键细胞器，具有复杂的 控制其动力学（融合，裂变）和周转（线粒体自噬）的过程。线粒体功能障碍是一种 在许多人类疾病包括COPD和IPF的发病机制中，我们有 表明线粒体功能障碍介导CS诱导的上皮细胞损伤/肺气肿 发育和博莱霉素（BLM）诱导的肺纤维化;有趣的是， 关键的线粒体自噬调节因子PTEN诱导的推定激酶-1（PINK 1）在CS临床前模型中具有保护作用。 诱导的肺气肿，而在BLM诱导的肺纤维化中，PINK 1依赖 线粒体自噬与受体相互作用蛋白激酶3（RIPK 3）的激活有关，RIPK 3是一种关键的信号激酶， 介导调节性坏死（坏死性凋亡）。我们已经发表了RIPK 3调节代谢过程， 器官组织，包括（FA）生物合成途径，并观察到脂肪酸合成酶的遗传缺陷， （FEV 1），肺纤维化加重。有趣的是，我们发现CS诱导的肺损伤可能引发 全身反应，包括对远端器官（肾脏）的损伤。此外，我们和其他人发现， 循环无细胞（cf）-线粒体DNA，一个确定的线粒体损伤和功能障碍的标志物， COPD和IPF患者的血浆或尿液中，cf-mtDNA序列变异性（异质性）可能起作用， 在肺部疾病的发病机制中起关键作用。这些有趣的数据表明线粒体途径 影响功能和临床表型（纤维化与肺气肿），并导致我们 提出以下假设：响应CS的线粒体功能障碍可以调节导致 COPD或IPF中的不同表型，包括PINK依赖性线粒体自噬和下游 RIPK 3的规则。此外，关键的代谢和线粒体信号，包括线粒体融合/分裂， 并且脂质代谢可以决定导致肺气肿或纤维化的细胞途径。血浆和/或尿液 cf-mtDNA以及线粒体异质性程度可能与IPF和COPD的严重程度相关。我们 我们将在以下USpecific目标中阐述我们的假设：USpecific目标1：确定功能 PINK 1调节RIPK 3信号在实验性肺气肿和纤维化中的意义具体目标2： 确定线粒体和代谢途径调节PINK 1-RIPK 3信号传导的机制 实验性肺气肿和纤维化具体目标3：评估循环或尿液cf-mtDNA是否是 与IPF和COPD的疾病严重程度相关。

Abstract Fibrosis and emphysema represent divergent clinical phenotypes that emerge during the pathogenesis of chronic lung diseases induced by cigarette smoke (CS). We have uncovered Udistinct mitochondrial and metabolic pathways in response to injurious stimuli that may underlie divergent pathways leading to fibrosis or emphysema outcomesU. Mitochondria are key organelles that regulate metabolism and energy generation, with complex processes governing their dynamics (fusion, fission), and turnover (mitophagy). Mitochondrial dysfunction is an emerging mechanism underlying the pathogenesis of many human diseases including COPD and IPF. We have demonstrated that mitochondrial dysfunction mediates CS-induced epithelial cell injury/emphysema development, and bleomycin (BLM)-induced pulmonary fibrosis; and interestingly, that genetic deficiency in the critical mitophagy regulator PTEN-induced putative kinase-1 (PINK1) is UprotectiveU in preclinical models of CS- induced emphysema while UdeleteriousU in BLM-induced pulmonary fibrosis. Moreover, PINK1-dependent mitophagy was linked to the activation of receptor-interacting protein kinase-3 (RIPK3), a key signaling kinase mediating regulated necrosis (necroptosis). We have published that RIPK3 regulates metabolic processes in organ tissue, including (FA) biosynthetic pathways, and observed that genetic deficiency in fatty acid synthase (FASN), aggravated pulmonary fibrosis. Interestingly, we have found that CS-induced lung injury may trigger systemic responses including injury to distal organs (kidney). Moreover, we and others have found that circulating cell-free (cf)-mtDNA, an established marker of mitochondrial injury and dysfunction, is regulated in plasma or urine of COPD and IPF patients, and that cf-mtDNA sequence variability (heteroplasmy) may play critical roles in the pathogenesis of lung diseases. These intriguing data suggest that mitochondrial pathways influence functional and clinical phenotypes (fibrosis vs. emphysema) in response to CS exposure and led us to propose the following Uhypotheses:U Mitochondrial dysfunction in response to CS can regulate pathways leading to divergent phenotype in COPD or IPF, including the activation of PINK-dependent mitophagy and downstream regulation of RIPK3. Furthermore, key metabolic and mitochondrial signals including mitochondrial fusion/fission and lipid metabolism may determine cellular pathways leading to emphysema or fibrosis. Plasma and/or urinary cf-mtDNA, as well as degree of mitochondrial heteroplasmy, may correlate with severity of IPF and COPD. We will address our hypotheses in the following USpecific Aims:U Specific Aim 1: To determine the functional significance of PINK1-regulated RIPK3 signaling in experimental emphysema and fibrosis. Specific Aim 2: To determine the mechanism(s) by which mitochondrial and metabolic pathways regulate PINK1-RIPK3 signaling in experimental emphysema and fibrosis. Specific Aim 3: To evaluate whether circulating or urinary cf-mtDNA is associated with severity of disease in IPF and COPD.