Epigenetics participate in neonatal CLD

描述(申请人提供)：早产和机械通气(MV)会引发肺部反应。这种反应导致以肺泡简化为特征的新生儿慢性肺病(CLD)。然而，早产和MV共同失调肺泡形成的机制还不是很清楚。一种潜在的机制是表观遗传学，它使用组蛋白共价修饰和DNA CpG甲基化来调节基因转录。早产羔羊在接受MV而不是高频鼻通气(HFNV)治疗时，会发生新生儿慢性阻塞性肺疾病。我们的其他新发现包括：1)组蛋白3(H3)的全基因组低乙酰化和高甲基化；2)胰岛素样生长因子-1(IGF-1)的表达增加；以及3)IGF-1基因座上的组蛋白编码中断。我们对IGF-1表达调控的关注是相关的，因为患有新生儿CLD的早产儿患者肺IGF-1表达增加。另一项新发现是，这些表观遗传变化不会发生在HFNV身上。令人振奋的新数据表明，MV期间的两种干预措施(组蛋白脱乙酰酶[HDAC]抑制剂；维生素A+维甲酸，VARA)改善了肺泡形成并改变了表观遗传学特征。这些新数据表明，表观遗传学参与了新生儿CLD。我们的中心假设是，与HFNV相比，早产和MV在新生儿CLD动物模型中调节肺中组蛋白共价修饰和DNA CpG甲基化。由于我们建议的重点是表观遗传机制，我们还将在MV期间使用HDAC抑制剂或VARA，以抑制MV单独引起的肺表观遗传学、组织学、呼吸系统气体交换和肺力学的失调。具体目标1将确定MV是否会导致肺内H3共价修饰和DNA甲基化的全基因组失调。具体目的2将确定MV是否在决定基因识别位点和基因转录起始、外显子选择、延长和终止的重要功能区域对IGF-1组蛋白共价修饰和DNA甲基化产生干扰。具体目标3将确定在MV期间肺IGF-1表达增加是否有助于肺泡简化和肺功能低下。我们的建议是创新的，因为它测试了早产和MV同时改变表观遗传特征和肺泡形成的假设。我们的研究设计从肺全基因组的组蛋白修饰和DNA CpG甲基化到IGF-1基因座上的组蛋白密码，并将结果与肺泡形成、呼吸系统气体交换和肺力学联系起来。我们的记录提供了信心，我们可以完成这些复杂和长期的研究，在这些研究中，我们将使用我们独特的新生儿CLD大型动物生理模型。我们将使用IGF-1作为范例，因为我们在IGF-1表观遗传学方面拥有独特的专业知识。我们的建议的意义在于，它有可能改变关于新生儿CLD分子和生理发病机制的范式。 与公共卫生相关：早产儿和MV结合起来失调肺泡形成的机制还没有很好的定义。一种潜在的机制是表观遗传学，它使用组蛋白共价修饰和DNA CpG甲基化来调节基因转录。我们的中心假设是，与HFNV相比，早产和MV在新生儿CLD动物模型中调节肺中组蛋白共价修饰和DNA CpG甲基化。

DESCRIPTION (provided by applicant): Preterm birth and mechanical ventilation (MV) trigger a pulmonary response. The response results in neonatal chronic lung disease (CLD), characterized by alveolar simplification. However, the mechanisms through which prematurity and MV combine to dysregulate alveolar formation are not well defined. A potential mechanism is epigenetics, which uses histone covalent modifications and DNA CpG methylation to regulate gene transcription. Premature lambs develop neonatal CLD when managed by MV but not high-frequency nasal ventilation (HFNV). Our other novel discoveries are that MV causes pulmonary 1) genome-wide hypoacetylation and hypermethylation of histone 3 (H3); 2) increased expression of insulin-like growth factor-1 (IGF-1); and 3) disruption of the histone code along the IGF-1 gene locus. Our focus on the regulation of IGF-1 expression is relevant because preterm humans with neonatal CLD have increased pulmonary IGF-1 expression. Another novel discovery is that these epigenetic changes do not happen with HFNV. Exciting new data suggest that two interventions (histone deacetylase [HDAC] inhibitors; vitamin A+retinoic acid, VARA) during MV improve alveolar formation and change epigenetic characteristics. These new data suggest that epigenetics participate in neonatal CLD. Our central hypothesis is that preterm birth and MV dysregulate histone covalent modifications and DNA CpG methylation in the lung compared to HFNV in a well-established animal model of neonatal CLD. Because the focus of our proposal is epigenetic mechanisms, we will also use HDAC inhibitors or VARA) during MV to inhibit the dysregulation caused by MV alone on pulmonary epigenetics, histology, respiratory gas exchange, and pulmonary mechanics. Specific Aim 1 will determine whether MV causes genome-wide dysregulation of H3 covalent modifications and DNA methylation in the lung. Specific Aim 2 will determine whether MV dysregulates IGF-1 histone covalent modifications and DNA methylation at functionally important regions that determine gene recognition sites and gene transcription initiation, exon selection, elongation, and termination. Specific Aim 3 will determine whether increased pulmonary IGF-1 expression during MV contributes to alveolar simplification and poor lung function. Our proposal is innovative because it tests the hypothesis that preterm birth and MV change epigenetic characteristics and alveolar formation in parallel. Our study design drills-down from pulmonary genome-wide histone modifications and DNA CpG methylation to the histone code along the IGF-1 gene locus, and relates the results to alveolar formation, respiratory gas exchange, and lung mechanics. Our track record provides confidence that we can accomplish these complex and long studies, in which we will use our unique large-animal, physiological model of neonatal CLD. We will use IGF-1 as a paradigm because of our unique expertise on IGF-1 epigenetics. The significance of our proposal is that it has the potential to shift the paradigm about both the molecular and physiologic pathogenesis of neonatal CLD. PUBLIC HEALTH RELEVANCE: The mechanisms through which prematurity and MV combine to dysregulate alveolar formation are not well defined. A potential mechanism is epigenetics, which uses histone covalent modifications and DNA CpG methylation to regulate gene transcription. Our central hypothesis is that preterm birth and MV dysregulate histone covalent modifications and DNA CpG methylation in the lung compared to HFNV in a well-established animal model of neonatal CLD.