Redox Regulation of Lung Mitochondrial Biogenesis in Sepsis/Pneumonia

描述(申请人提供)：这是一份修订后的申请，旨在研究线粒体生物发生和有丝分裂在金黄色葡萄球菌引起的实验性脓毒症和急性肺损伤(ALI)中的调节和作用。它与ICU患者相关，这些患者在严重脓毒症和ARDS/多器官功能障碍综合征(MODS)的初始发作中幸存下来，但死于以效应细胞凋亡、抗炎细胞因子过度表达、促炎细胞因子合成抑制和反复感染为特征的所谓“免疫瘫痪”。本课题组发现的一个重要的促分解机制是通过氧化还原调节的线粒体生物发生双基因组转录网络对先天性免疫的强大控制，该网络由血红素加氧酶-1/一氧化碳系统(HO-1/CO)的诱导而强烈激活，以保护能量代谢和线粒体质量，但我们认为这也可能促进受损细胞器的清除(有丝分裂)，限制MODS的进一步炎症损伤。已发表的和初步的数据提出了一种新的可能性，即线粒体生物发生的转录程序将有丝分裂、抗炎和抗氧化防御整合到一个连贯的损伤解决网络中，肺泡上皮是ALI中肺损伤的主要部位。我们认为，线粒体生物发生程序通过HO-1/CO激活NFe212和NRF-1，导致1)抗炎SOCS3和IL10基因表达，2)抑制炎症体介导的IL-1β产生，3)通过Bnip3和ATG5激活有丝分裂，促进肺泡上皮细胞存活和屏障功能障碍的解决，从而介导肺保护。利用活体金黄色葡萄球菌败血症和小鼠肺炎以及互补的肺细胞研究，我们将调查这种线粒体生物发生的集成遗传网络如何影响肺部炎症和ALI的解决。概念验证将意味着脓毒症/肺炎的肺具有反调节保护措施，包括诱导线粒体生物发生以防止全身炎症反应对线粒体的进一步损害，并清除受损的线粒体以恢复线粒体的健康和肺泡上皮修复的能力，例如通过2型(AT2)细胞我们建议进行翻译研究来检验这一概念在人类肺弥漫性肺泡损伤(DAD)中的概念，如果成功，将为改善线粒体功能和解决ALI/ARDS开辟治疗途径。目的1：探讨NFe2l2和NRF1诱导金黄色葡萄球菌败血症和肺炎小鼠肺线粒体生物发生是否上调SOCS3和IL10抗炎基因的表达，抑制caspase1的裂解和IL-1β的产生，从而减轻肺部炎症和ALI。目的：利用功能得失研究确定NFe2l2和NRF1诱导肺线粒体生物发生a)是否调节自噬基因Bnip3和ATG5以及b)通过HO-1/CO相关线粒体ROS的产生激活促生存有丝分裂。目的：探讨ALI/ARDS患者肺泡上皮细胞线粒体生物发生与有丝分裂吞噬的程度、位置及其与正常肺组织的关系。这些目标的完成将把线粒体生物发生的转录调节与有丝分裂、免疫反向调节、抗氧化防御和细胞生存联系起来。对人类ALI/ARDS的积极预测研究将对我们理解脓毒症和MODS的解决产生重要影响。

DESCRIPTION (provided by applicant): This is a revised application to study the regulation and the role of mitochondrial biogenesis and mitophagy in experimental sepsis and acute lung injury (ALI) caused by S. aureus. It is relevant to ICU patients who survive an initial episode of severe sepsis and ARDS/multiple organ dysfunction syndrome (MODS), but die with so- called "immune paralysis" characterized by effector cell apoptosis, anti-inflammatory cytokine over-expression, suppression of pro-inflammatory cytokine synthesis and recurrent infections. One important pro-resolution mechanism discovered by our group is the powerful control over innate immunity by the redox-regulated bi- genomic transcriptional network of mitochondrial biogenesis, which is strongly activated by the induction of the heme oxygenase-1/carbon monoxide system (HO-1/CO) to protect energy metabolism and mitochondrial mass, but which we think may also promote the clearance of damaged organelles (mitophagy) and limit further inflammatory damage in MODS. Published and preliminary data raise the novel possibility that the transcriptional program for mitochondrial biogenesis integrates mitophagy, counter-inflammation, and anti- oxidant defenses into a coherent injury resolution network in alveolar epithelium, the major site of lung damage in ALI. We propose that the program of mitochondrial biogenesis mediates lung protection through HO-1/CO activation of Nfe2l2 and NRF-1 leading to 1) anti-inflammatory Socs3 and IL10 gene expression, 2) suppression of inflammasome-mediated IL-1¿ production, and 3) activation of mitophagy through Bnip3 and Atg5, promoting alveolar epithelial cell survival and resolution of barrier dysfunction. Using live S. aureus sepsi and pneumonia in mice and complementary lung cell studies, we will investigate how this integrated genetic network of mitochondrial biogenesis impacts on lung inflammation and ALI resolution. Proof-of-concept would mean the lung in sepsis/pneumonia has counter-regulatory safeguards involving the induction of mitochondrial biogenesis to prevent further mitochondrial damage from the systemic inflammatory response and clear damaged mitochondria to restore mitochondrial health and capacity for alveolar epithelial repair, e.g. though the type 2 (AT2) cell We propose translational studies to test the concept in diffuse alveolar damage (DAD) in human lung, which if successful, would open up therapeutic avenues for the improvement of mitochondrial function and the resolution of ALI/ARDS. Our Specific Aims are: Aim 1: Determine whether Nfe2l2 and NRF1 induction of lung mitochondrial biogenesis in murine S. aureus sepsis and pneumonia up-regulates Socs3 and Il10 anti-inflammatory gene expression, suppresses caspase1 cleavage and IL-1¿ production and mitigates lung inflammation and ALI. Aim 2: Use gain and loss of function studies to determine whether Nfe2l2 and NRF1 induction of lung of mitochondrial biogenesis a) regulates the autophagy genes Bnip3 and Atg5 and b) activates pro- survival mitophagy through HO-1/CO-related mitochondrial ROS generation in murine S. aureus pneumonia. Aim 3: Assess the extent, location, and relationship of mitochondrial biogenesis to mitophagy in the alveolar epithelium of human ALI/ARDS patients compared with healthy human lung. Completion of these Aims would link transcriptional regulation of mitochondrial biogenesis to mitophagy and to immune counter-regulation, anti-oxidant defenses, and cell survival. Positive predictive studies in human ALI/ARDS would have a high impact on our understanding of the resolution of sepsis and MODS.