Foxf1 Transcription Factor in Development of Pulmonary Capillaries

描述（由申请人提供）：支气管肺发育不良（BPD）是一种慢性肺部疾病，发生于机械通气和高水平补充氧气后的早产儿。虽然早产新生儿的存活率由于最近围产期护理的改善而增加，但BPD仍然是早产的严重和常见并发症，在美国每年影响约15，000名婴儿。患有BPD的婴儿在幼儿期呼吸道疾病和死亡的风险较高。BPD具有长期的呼吸和神经发育并发症，这些并发症超过了儿童期，并增加了医疗保健费用。鉴于BPD的预防和治疗缺乏重大改进，因此非常需要创新的分子方法来补充现有的BPD疗法。BPD治疗的有前途的治疗方法包括增加出生后的血管生成和保护肺泡内皮细胞免于机械通气和高水平氧引起的损伤后的凋亡。根据我们的初步结果，我们认为叉头盒F1（Foxf 1）转录因子（也称为HFH-8和Freac-1）在这两个过程中起着关键作用，因此，靶向Foxf 1可以有益于BPD儿童的化学预防和治疗。我实验室发表的研究表明，Foxf 1在胚胎和新生儿肺的肺内皮细胞（EC）中表达。Foxf 1无效等位基因杂合子小鼠表现出肺发育不全，肺泡毛细血管数量减少，EC凋亡增加，新生儿早期死亡率增加。近年来，在30%的人类肺泡毛细血管发育不良（ACD）患者中发现了FoxF 1基因位点的基因组突变，ACD是一种先天性致死性肺病。肺Foxf 1 mRNA和蛋白水平降低新生小鼠暴露于高氧，小鼠模型的BPD。Foxf 1水平降低与高氧治疗的新生小鼠和BPD患者的肺血管损失相关。鉴于Foxf 1在小鼠和人类肺血管发育中的关键作用，确定Foxf 1在BPD发病机制中的作用非常重要。我们将使用新生小鼠中高氧介导的肺损伤作为BPD模型来检验这一假设，即Foxf 1通过刺激血管生成和增加内皮细胞的存活来维持高氧损伤后的正常肺形态发生。在目的I中，我们将使用两种具有Foxf 1缺陷的转基因小鼠系（Foxf 1小鼠和Tie 2-Cre-fl/fl ER Foxf 1小鼠）确定在BPD模型中Foxf 1是否是形成新的肺毛细血管所需的。在目的II中，我们将确定Foxf 1是否直接调节抗凋亡基因的表达，以及是否是BPD模型中内皮细胞存活所必需的。由于我们研究的长期目标是找到预防人类患者BPD的新型治疗药物，因此在Aim III中，我们将确定新生儿肺部Foxf 1水平的增加是否会加速血管形成，增加EC存活率并预防BPD。通过药理学方法（TAT-Foxf 1融合蛋白）或遗传学方法（内皮细胞中多西环素诱导的Foxf 1过表达），高氧处理的新生小鼠中的Foxf 1水平将增加。这些研究的完成将确定增加Foxf 1水平是否是一种有前途的治疗方法，以防止内皮细胞凋亡和诱导血管生成的BPD患者。 公共卫生相关性：Foxf 1转录因子是小鼠和人类肺血管发育的重要和临床相关的转录调节因子，但其在支气管肺发育不良（BPD）中的作用尚不清楚。使用两个新的小鼠模型与Foxf 1缺陷，我们建议，以确定是否需要Foxf 1维持出生后的肺形态发生刺激血管生成和增加高氧介导的损伤后的内皮细胞（EC）的生存，小鼠模型BPD。我们还建议使用细胞穿透性TAT-Foxf 1融合蛋白，一种新的治疗剂，以确定是否增加新生小鼠Foxf 1将促进高氧肺损伤后血管修复，减少EC凋亡和预防BPD。

DESCRIPTION (provided by applicant): Bronchopulmonary dysplasia (BPD) is a chronic lung disease that occurs in preterm infants following mechanical ventilation and high levels of supplemental oxygen. While survival of premature newborns has increased due to recent improvements in perinatal care, BPD remains a serious and common complication of prematurity, affecting approximately 15,000 infants annually in USA. Infants with BPD are at higher risk of respiratory morbidity and mortality in early childhood. BPD has long-term respiratory and neurodevelopmental complications that reach beyond childhood and increase health care costs. Given the lack of major improvements in prevention and treatment of BPD, there is a major need for innovative molecular approaches to complement existing BPD therapies. Promising therapeutic approaches for BPD treatment include increasing postnatal angiogenesis and protection of alveolar endothelial cells from apoptosis after the injury caused by mechanical ventilation and high levels of oxygen. Based on our preliminary results, we believe that Forkhead Box F1 (Foxf1) transcription factor (also known as HFH-8 and Freac-1) plays a key role in both these processes and therefore, targeting the Foxf1 can be beneficial for both chemoprevention and treatment of children with BPD. Published studies from my laboratory have demonstrated that Foxf1 is expressed in pulmonary endothelial cells (EC) of embryonic and neonatal lungs. Mice heterozygous for the Foxf1 null allele exhibited lung hypoplasia, decreased number of alveolar capillaries, increased apoptosis of EC, and increased mortality in the early neonatal period. Genomic mutations in FoxF1 gene locus were recently found in 30% of human patients with Alveolar Capillary Dysplasia (ACD), a congenital lethal lung disease. Pulmonary Foxf1 mRNA and protein levels are reduced in newborn mice exposed to hyperoxia, a mouse model of BPD. Diminished Foxf1 levels are associated with loss of pulmonary vasculature in hyperoxia-treated newborn mice and human patients with BPD. Given the critical role of Foxf1 for pulmonary vascular development in mice and humans, it is important to determine the role of Foxf1 in the pathogenesis of BPD. We will use hyperoxia- mediated lung injury in newborn mice as a model of BPD to test the hypothesis that Foxf1 is required to maintain normal lung morphogenesis after hyperoxia injury by stimulating angiogenesis and increasing survival of endothelial cells. In Aim I, we will determine whether Foxf1 is required for formation of new pulmonary capillaries in a BPD model using two transgenic mouse lines with Foxf1 deficiency: Foxf1 mice and Tie2-Cre- fl/fl ER Foxf1 mice. In Aim II, we will determine whether Foxf1 directly regulates expression of anti-apoptotic genes and is required for survival of endothelial cells in a BPD model. Since the long-term goal of our studies is to find novel therapeutic agents preventing BPD in human patients, in Aim III we will determine whether increasing Foxf1 levels in neonatal lungs will accelerate vessel formation, increase EC survival and prevent BPD. Foxf1 levels in hyperoxia-treated newborn mice will be increased by either pharmacological approach (TAT-Foxf1 fusion protein) or genetic approach (Doxycycline-inducible over-expression of Foxf1 in endothelial cells). Completion of these studies will determine whether increasing Foxf1 levels is a promising therapeutic approach to prevent endothelial apoptosis and induce angiogenesis in BPD patients. PUBLIC HEALTH RELEVANCE: Foxf1 transcription factor is an important and clinically-relevant transcriptional regulator of pulmonary vascular development in mice and humans, but its role in Bronchopulmonary dysplasia (BPD) remains unknown. Using two novel mouse models with Foxf1 deficiency, we propose to determine whether Foxf1 is required to maintain postnatal lung morphogenesis by stimulating angiogenesis and increasing survival of endothelial cells (EC) after hyperoxia-mediated injury, a mouse model of BPD. We also propose to use cell-penetrating TAT-Foxf1 fusion protein, a novel therapeutic agent, to determine whether increasing Foxf1 in newborn mice will promote vascular repair after hyperoxia lung injury, decrease EC apoptosis and prevent BPD.