Mechanisms controlling early human lung development

摘要： 唐氏综合征(DS)是最常见的人类染色体异常，在中国每800名新生儿中就有1名患病 美国。尽管唐氏综合症会影响到许多器官系统，但肺病和心脏病是 DS各年龄段的主要死因。在DS患者中报告了几种先天性肺畸形。 包括呼吸道分支缺陷，分支代数减少25%，肺 发育不全、囊性病变和血管缺陷导致肺动脉高压。此外，DS患者还可以 伴有吞咽困难和/或支气管软化的上呼吸道肌张力降低。我们已经开发出一种 允许实时量化分支的人类体外肺分支形态发生模型，以及 在这个过程中，我们可以询问平滑肌的作用。我们的初步数据表明， SMC蠕动似乎损害了人DS肺外植体的分支。我们最近还展示了 正常人胎肺间充质平滑肌细胞多样性转录图谱的研究 纸巾。我们的初步数据确定了特定人群特有的分子标记，包括血管和 呼吸道平滑肌细胞。因此，我们推测DS患者的肺发育异常是由 平滑肌细胞功能、表型和异质性的细胞自主性缺陷。在目标1中，我们将 验证DS患者肺SMC的气道分支相关功能和表型受损的假设 应用我们的人胎肺体外培养系统进一步研究DS胎肺的分支和蠕动 纸巾。我们还将测试钙介导的SMC收缩和蠕动变化是否正常 DS肺SMC。在目标2中，我们将确定DS胎儿的气道平滑肌细胞多样性是否异常。 用单细胞转录组分析正常和DS胎儿肺中SMC表型的多样性。 我们还将通过同时比较正常肺血管和DS肺血管来确定任何改变的特异性 平滑肌细胞表型异质性。我们提出的研究将是第一个检验新假说的研究 关于早期DS肺SMC表型和功能的主要缺陷 在生理、形态发生、细胞和分子水平上提供洞察。改进了预防战略， DS患者肺部疾病的改善或逆转将取决于对其发病机制的详细了解 这些疾病。这里提出的研究旨在提供关于以下方面的基本知识 异常的病理生理学有助于DS肺的发育异常，并可能识别 干预的治疗靶点。

Abstract: Down syndrome (DS) is the most common human chromosomal anomaly and affects 1 in 800 newborns in the United States. Although Down syndrome can affect many organ systems, lung and heart disease are the leading causes of death at all ages in DS. Several congenital lung anomalies are reported in DS patients including airway branching defects, with a 25% decrease in number of branch generations, pulmonary hypoplasia, cystic lesions and vascular defects leading to pulmonary hypertension. In addition, DS patients can present with reduced upper airway muscle tone with dysphagia and/or bronchomalacia. We have developed a human ex vivo lung branching morphogenesis model that allows for branching quantification in real time, and in which we can interrogate the contributions of smooth muscle. Our preliminary data suggests that defects in SMC peristalsis appear to impair branching in human DS lung explants. We have also recently demonstrated the ability to transcriptionally profile mesenchymal smooth muscle cell diversity in normal human fetal lung tissues. Our preliminary data identify molecular markers unique to defined populations including vascular and airway smooth muscle cells. Therefore, we hypothesize that abnormal lung development in DS is caused by cell autonomous deficiencies in smooth muscle cell function, phenotype and heterogeneity. In aim 1, we will test the hypothesis that airway branching-associated function and phenotype of lung SMCs is impaired in DS using our ex vivo fetal human lung culture system to further examine branching and peristalsis in DS fetal lung tissues. We will also test whether calcium-mediated changes in SMC contraction and peristalsis are normal in DS lung SMCs. In aim 2, we will determine whether airway smooth muscle cell diversity is abnormal in DS fetal lung using single cell transcriptomics to assess the diversity of SMC phenotypes in normal and DS fetal lung. We will also define the specificity of any alterations by simultaneously comparing normal and DS lung vascular smooth muscle cell phenotypic heterogeneity. Our proposed studies will be the first to test novel hypotheses about primary deficiencies in early DS lung SMC phenotypes and function using cutting-edge methods that will provide insight at the physiological, morphogenic, cellular and molecular levels. Improved strategies to prevent, ameliorate or reverse lung disease in DS will be contingent upon a detailed understanding of the pathogenesis of these diseases. The studies proposed here are designed to provide fundamental knowledge about the abnormal pathophysiology contributing to developmental abnormalities in DS lung, and may identify therapeutic targets for intervention.