Let-7b in BPD

项目摘要 支气管肺发育不良（BPD）在极低出生体重（ELBW）婴儿中很常见。 最近，我们发现最强的生物标志物信号是microRNA let-7 b-5 p，为46倍 随后发生严重BPD的婴儿出生时血液中的浓度增加（p<0.001）（与 无BPD）。我们还发现let-7 b-5 p在第一天增加了14倍， 1在随后发展为BPD的婴儿的气管吸出物中。在细胞培养中，气道上皮细胞 是let-7 b-5 p的主要来源，随氧浓度升高而增加。我们发现过量的let-7 b抑制了 血管生成，并且在高氧期间抑制let-7 b改善新生小鼠的肺发育。 在“BPD中的Let-7 b”项目中，我们将基于我们令人兴奋的let-7 b-5 p发现作为一种强有力的 BPD的生物标志物，并确定其与肺发育和BPD的相关性。我们将测试中央 假设miRNA let-7 b-5 p是（a）用于分期、监测疾病 进展和对治疗的反应，（B）通过氧化应激从气道上皮细胞释放， (c)是支气管肺发育不良中血管生成失调的原因，和（d） let-7 b信号传导的抑制改善肺血管生成并减弱BPD表型。 我们将通过以下具体目标来检验假设： 具体目标1 -确定极早产儿的血浆let-7 b-5 p浓度是否随肺 疾病进展并与治疗反应相关。 Let-7 b-5 p将在来自良好表征的前瞻性队列的连续血浆样品中测量。 150名早产儿我们将定义let-7 b-5 p在呼吸系统疾病中的时间变化 严重程度、BPD分期和36周PMA时的肺力学，以及临床治疗。 特定目的2 -确定新生小鼠肺气道上皮细胞释放Let-7 b的机制 为了证实氧化应激释放let-7 b-5 p是关键的上游机制，我们将使用 新型转基因小鼠。我们将检验线粒体ROS减少会降低let-7 b-5 p的假设。 和BPD表型，并确定Nrf 2和NF-kB信号转导的作用，使用特异性 细胞培养模型中的抑制剂/调节剂。 具体目标3 -确定过量let-7 b-5 p信号传导对肺微血管发育的影响。 我们将检验let-7 b-5 p过度表达诱导肺微血管损伤的假设， 发育，甚至在常氧下在新生小鼠中诱导BPD表型，以及抑制let-7 b-5 p 改善高氧暴露新生小鼠肺（BPD模型）的肺发育。

Project Summary Bronchopulmonary dysplasia (BPD) is common in extremely low birth weight (ELBW) infants. Recently, we discovered that the strongest biomarker signal was of microRNA let-7b-5p, with a 46-fold increase (p<0.001) at birth in the blood of infants who subsequently developed severe BPD (versus no BPD) many weeks later at 36w post-menstrual age. We also found a 14-fold increase of let-7b-5p on day 1 in the tracheal aspirate of infants who subsequently developed BPD. In cell culture, airway epithelial cells were the primary source of let-7b-5p, that increased with hyperoxia. We found that excessive let-7b inhibits angiogenesis, and that let-7b inhibition during hyperoxia improves lung development in newborn mice. In the “Let-7b in BPD” project, we will build upon our exciting discovery of let-7b-5p as a robust biomarker of BPD, and determine its relevance to lung development and BPD. We will test the central hypotheses that miRNA let-7b-5p is (a) a valuable biomarker for staging, monitoring disease progression and response to therapy, (b) is released from airway epithelial cells by oxidative stress, (c) is a contributor to dysregulated angiogenesis in bronchopulmonary dysplasia, and (d) that inhibition of let-7b signaling improves lung angiogenesis and attenuates the BPD phenotype. We will test the hypotheses by the following Specific Aims: Specific Aim 1 – Determine if plasma let-7b-5p concentrations in extremely preterm infants track with lung disease progression and correlate with response to therapy. Let-7b-5p will be measured in serial plasma samples from a well characterized prospective cohort of 150 extremely preterm infants. We will define the temporal changes in let-7b-5p with respiratory illness severity, BPD staging and lung mechanics at 36w PMA, and with clinical therapies. Specific Aim 2 – Determine the mechanisms of Let-7b release by newborn mouse lung airway epithelium To confirm that the let-7b-5p release by oxidative stress is the key upstream mechanism, we will use novel transgenic mice. We will test the hypothesis that reduction of mitochondrial ROS reduces let-7b-5p and the BPD phenotype, and determine the role of Nrf2 and NF-kB signaling using specific inhibitors/modulators in cell culture models. Specific Aim 3 – Determine effects of excessive let-7b-5p signaling on lung microvascular development. We will test the hypothesis that over-expression of let-7b-5p induces impaired lung microvascular development, inducing a BPD phenotype in newborn mice even in normoxia, and that inhibition of let-7b-5p improves lung development in hyperoxia- exposed newborn mouse lung (BPD model).