Wnt Signaling in Bronchopulmonary Dysplasia

项目总结 摘要支气管肺发育不良(BPD)是早产的主要并发症，并有长期的后遗症。 幸存者和没有根治的治疗。促进BPD表型受损的分子机制 肺泡化和纤维化尚不清楚，这种知识差距阻碍了新的BPD的发展。 治疗。BPD主要影响在肺发育的脆弱囊状阶段出生的早产儿 (妊娠23-32周)，因高氧、炎症和机械拉伸造成的损伤。我们的前辈 工作的重点是了解球囊阶段损伤如何扰乱正常的发育模式 小路。其中一个信号通路，Wnt，在小管期达到激活峰值，并逐渐 在球囊阶段减少，足月出生时几乎不存在活跃的Wnt信号。我们最近 BPD患儿肺组织中Wnt信号异常激活。此外，外生性 在我们的3D人体模型和我们的高氧小鼠模型中Wnt信号的激活足以复制 BPD在体外和体外的表型，提示Wnt是BPD发病的重要驱动因素。 转化生长因子-(转化生长因子-)是正常肺发育所必需的另一条途径 过多的发育会导致肺泡化和纤维化。球囊期显露 肺对高氧损伤导致活化的Wnt和转化生长因子-信号增加，我们能够 通过单独激活Wnt诱导转化生长因子-信号转导。我们的初步数据显示高氧血症 暴露于囊状期肺导致配体WNT5A和WNT5A间充质表达增加 Wnt调节剂r-Respondin-3(RSPO_3)在上皮细胞中的表达增加，提示Wnt具有空间特异性 配体在该模型中的表达。因此，我们假设肺球囊期的损伤 发育导致RSPO_3在上皮细胞的异常表达和间质细胞的异常表达 这种增加的Wnt信号促进了下游转化生长因子-信号的激活，从而导致 BPD的肺泡化和纤维化受损。我们的具体目标是：1)确定WNT的角色 在BPD中介导受损的肺泡化和纤维化的信号转导，以及2)确定其机制 高氧暴露导致Wnt通路激活和转化生长因子-信号上调。成功 这些具体目标的完成将提高我们对WNT信号对 对发育中的肺的损伤反应，并为预防BPD的靶向治疗提供了基础。另一个 这项提议的主要目标是创建一个有重点和结构化的职业发展计划，该计划将提供 对研究人员进行必要的培训，使其成为一名独立的内科医生兼科学家，并在 BPD的分子机制。本提案中的实验和培训计划创建了以下结构 一个专注于发育性肺部疾病的独立、严格的研究计划的发展。

PROJECT SUMMARY Bronchopulmonary dysplasia (BPD) is a leading complication of preterm birth, with long term sequelae in survivors and no curative treatment. The molecular mechanisms that promote the BPD phenotype of impaired alveolarization and fibrosis are not known, and this knowledge gap impedes the development of new BPD therapies. BPD primarily affects preterm infants born during the vulnerable saccular stage of lung development (23-32 weeks gestation), with resulting injury from hyperoxia, inflammation, and mechanical stretch. Our prior work has focused on understanding how saccular stage injury disrupts the normal patterning of developmental pathways. One of these signaling pathways, Wnt, has peak activation in the canalicular stage and gradually decreases during the saccular stage, with little active Wnt signaling present at term birth. We recently demonstrated aberrant activated Wnt signaling in the lungs of infants with BPD. Moreover, exogenous activation of Wnt signaling in our 3D human model and our hyperoxia mouse model is sufficient to reproduce the BPD phenotype in vitro and ex vivo, suggesting that Wnt is an important driver of BPD pathogenesis. Transforming growth factor-(TGF-) is another developmental pathway necessary for normal lung development that in excess contributes to impaired alveolarization and fibrosis. Exposure of saccular stage lung to hyperoxia injury results in increased activated Wnt and TGF- signaling, and we are able to experimentally induce TGF- signaling by activation of Wnt alone. Our preliminary data show that hyperoxia exposure of saccular stage lung results in increased mesenchymal expression of ligand Wnt5A as well as increased epithelial expression of Wnt modulator r-spondin-3 (RSPO3), suggesting spatial specificity of Wnt ligand expression in this model. We therefore hypothesize that that injury during the saccular stage of lung development causes aberrant epithelial expression of RSPO3 and aberrant mesenchymal expression of Wnt5A, and this increased Wnt signaling facilitates the activation of downstream TGF- signaling, resulting in impaired alveolarization and fibrosis seen in BPD. Our specific aims are to: 1) determine the role of Wnt signaling in mediating impaired alveolarization and fibrosis in BPD, and 2) to identify the mechanisms whereby hyperoxia exposure results in Wnt pathway activation and up-regulation of TGF- signaling. Successful completion of these specific aims will improve our understanding of the contribution of Wnt signaling to the injury response in the developing lung and provide a foundation for targeted therapies to prevent BPD. Another major objective of this proposal is to create a focused and structured career development plan that will provide the necessary training for the researcher to become an independent physician-scientist with expertise in the molecular mechanisms of BPD. The experiments and training program in this proposal create the structure for the growth of an independent rigorous research program focused on developmental lung diseases.