支气管肺发育不良血管发育机制：谷氧还蛋白通过S-谷胱甘肽化机制介导NF-κB调节生理与病理性血管形成假说

Interactions between airways and blood vessels are critical for normal lung development, suggesting that a coordinated and timely release of vascular-specific growth factors from respiratory epithelial cells promotes alveolar development. Perinatal lung injury in neonates born during the late canalicular stage of lung development disrupts the normal sequence of lung growth, resulting in a histological pattern of “alveolar simplification” (fewer and larger alveoli with fewer septae), loss of small pulmonary arteries, and decreased capillary density. .Grx1 is described as ubiquitously present within the cell. Under physiologic conditions, Grx acts specifically to remove conjugated glutathione from proteins, a process known as de-glutathionylation. Given the specificity and regulation of PSSG content, this posttranslational modification has the ability to regulate cell-signaling cascades. Recent studies demonstrated that the NF-κB pathway is inhibited by PSSG to the production of inflammatory mediators. During development, the NF-κB family of transcription factors plays a key role in innate immunity. NF-κB is one of the pivotal regulators of pro-inflammatory gene expression, and the aberrant regulation of NF-κB activity has been implicated in the pathogenesis of in a number of pulmonary diseases including acute lung injury, asthma, BPD and cystic fibrosis. In the vasculature, increased NF-κB activity plays a key pathogenic role. A number of NF-κB-regulated inflammatory cytokines are potent angiogenic stimulators. Moreover, signaling via the vascular endothelial growth factor (VEGF) signaling pathway appears to specifically drive postnatal angiogenesis and alveolarization in an NF-κB-dependent manner. However, although extensive data links increased NF-κB to pulmonary and vascular pathology, a physiological role for NF-κB in pulmonary vascular development has not been previously described..The aim of the present study was to perform a comprehensive analysis if the Grx1/NF-κB activity is critical for neonatal pulmonary angiogenesis homeostasis. We intend to explore the initial factor of BPD: to identify the level of constitutive NF-κB activity in the neonatal pulmonary endothelium in the Grx1 knockdown mice and to investigate if pharmacological blockade of NF-κB in neonatal mice could reduce pulmonary capillary density and induce the alveolar simplification. At last if NF-κB regulates the expression of the proangiogenic molecule, VEGFR2, inflammatory cytokines in the developing pulmonary vasculature through regulation of PSSG..Taken together, our data have palpable clinical and biological relevance. This study may be the first to identify NF-κB as an essential transcriptional regulator of secondary septation and angiogenesis in the developing lung. We speculate that disruption of Grx1/NF-κB signaling may contribute to the pathogenesis of BPD, by which to develop the interventions to guide the physiological capillary formation.

支气管肺发育不良(BPD)血管发育紊乱从而扰乱肺泡上皮和毛细血管之间的协调作用是BPD发病重要机制。谷氧还蛋白(Grx1)可以通过蛋白质谷胱甘肽化(PSSG)调控NF-κB信号通路介导肺微血管发育，但与BPD发生的具体关系尚未完全阐明。我们推测BPD氧化状态下Grx1/PSSG通过氧化还原NF-κB(提高其活性)调节炎性因子及VEGF之间平衡进而影响肺血管发育，引起BPD病理改变，肺泡间隔扩大。我们拟利用BPD小鼠模型探讨BPD发生始动因素：肺微血管发育紊乱-炎症介质诱导的病理性血管增生紊乱阻碍VEGF介导引起生理肺微血管有序发育。进一步通过干预谷氧还蛋白(Grx1)以及阻断NF-κB信号明确BPD发生中Grx1通过对NF-κB谷胱甘肽化调节引起病理性肺微血管形成的核心机制，并试图通过干预Grx1信号通路治疗BPD，引导生理性毛细血管形成。力争在BPD发病机制血管假说方面获得有益进展。

支气管肺发育不良(BPD)是早产儿高氧机械通气引起的最常见并发症，具有很高的发病率和死亡率，并且其严重后果一直延续到成年期。BPD主要累及早产儿，这与成人急性肺损伤后肺泡的异常修复不同，发育因素在此病病理生理中起重要作用。随着对BPD发病机制认识的深入，肺血管发育紊乱这一典型病理特征在BPD发生机制中逐渐受到重视，现已成为新的研究热点。. Grx1基因可以催化降低蛋白谷胱甘肽化水平，而蛋白谷胱甘肽化可以稳定HIF-1α从而阻止其降解，所以Grx1反应性增加不利于稳定HIF-1α信号。敲出肺谷氧还蛋白(Grx1)可增加缺氧诱导因子-1α（Hypoxia inducible factor, HIF-1α）稳定性可能是支气管肺发育不良（bronchopulmonary dysplasia，BPD）的重要发病机制。截至目前，谷胱甘肽化对HIF-1α的稳定性的作用尚未阐释清楚。在该项目中，我们研究了是否可通过敲出Grx1调节HIF-1α稳定性，从而减轻BPD小鼠肺部病理变化。包括肺部微血管形成和肺泡形成。研究发现，敲出Grx1可显著性地降低GSH表达水平、增加GSSG含量和GSSG/GSH比值。高氧暴露新生小鼠的肺泡数量、肺部微循环中毛细血管数和存活率均显著提升。. 敲出Grx1可通过增加肺组织中HIF-1α谷胱甘肽化水平提高其稳定性，还可增加血管生长因子(VEGFA)的表达。高氧暴露后，HIF-1α抑制剂YC-1可抵消Grx1敲出对内皮细胞增殖的作用，可抵消敲出Grx1对新生小鼠高氧暴露肺的保护作用，证明HIF-1α可介导VEGFA信号通路，HIF-1α稳定性在肺部微循环发育中发挥着至关重要作用，提示为临床治疗早产儿BPD找到了潜在治疗靶点。