Respiratory sphingolipid synthesis involved in airway hyperreactivity and viral-triggered asthma

项目摘要 哮喘是由遗传背景和环境之间复杂的相互作用引起的 触发器17 q21哮喘易感位点与儿童哮喘密切相关， ORMDL3. ORMDL 3调节丝氨酸-棕榈酰辅酶A转移酶（SPT），其为 鞘脂的从头合成。我们证明，SPT活性降低会导致 气道高反应性此后，越来越多的证据表明， 在气道上皮细胞和ORMDL 3相关哮喘的动物模型中改变。我们有 最近表明，哮喘儿童的鞘脂合成减少，特别是在 存在哮喘风险的17 q21基因型。17 q21基因型也与以下风险有关： 人鼻病毒（HRV）呼吸道感染后发生哮喘。这是相关 因为心率变异性也是哮喘发作的最常见诱因。 小鼠和气道上皮细胞的初步数据支持， HRV感染与鞘脂水平和基因表达的相似性 缺乏，我们假设HRV感染可以进一步损害鞘脂的合成。我们 拟研究心率变异性对哮喘儿童鞘脂合成的影响， 气道上皮细胞。这些研究可以进一步巩固鞘脂的核心作用 在哮喘发病机制中， 17 q21基因型与哮喘的关系提出了两个具体目标来评估总体假设 鞘脂从头合成途径不仅对哮喘发病机制至关重要， 这也是哮喘发作最常见的诱因。在目标1中，我们将确定 哮喘和HRV感染儿童呼吸道鞘脂合成。 将在鼻液、血液中评估鞘脂，并获得鼻细胞中的基因表达 在HRV引发的哮喘发作期间和之后，在子目标中，我们 将评估HRV对鞘脂代谢和基因表达的影响， 具有常见17 q21哮喘变异纯合子的人气道上皮细胞（HAEC） 导致哮喘儿童的血鞘脂减少。港灯从一个既有 来自成人捐赠者的生物储存库和来自儿童的鼻刷， 将用HRV和RSV感染界面，并评价对鞘脂合成的影响。 对于目标2，我们将检验以下假设： 鞘氨醇1-磷酸和鞘氨醇1-磷酸，我们发现在SPT缺乏， 具有17 q21哮喘风险基因型的儿童导致气道高反应性。总体而言，这些 这些研究不仅揭示了鞘脂在哮喘发病机制中的作用， 与其最常见的触发因素有关，但可能导致新的治疗方法， 鞘脂代谢

PROJECT SUMMARY Asthma results from a complex interplay between genetic background and environmental triggers. The 17q21 asthma susceptibility locus is strongly linked to childhood asthma through ORMDL3. ORMDL3 regulates serine-palmitoyl CoA transferase (SPT), the critical enzyme for the de novo synthesis of sphingolipids. We demonstrated that decreased SPT activity leads to airway hyperreactivity. There has since been increasing evidence that sphingolipid metabolism is altered in airway epithelial cells and animal models of ORMDL3-associated asthma. We have recently shown that children with asthma have decreased sphingolipid synthesis, especially in the presence of asthma risk 17q21 genotypes. 17q21 genotypes are also linked to the risk of developing asthma following respiratory infections with human rhinovirus (HRV). This is relevant as HRV is also the most common trigger for asthma attacks. Supported by preliminary data in mice and airway epithelial cells demonstrating strong similarities in sphingolipid levels and gene expression between HRV infection and sphingolipid deficiency, we hypothesize that HRV infection can further impair sphingolipid synthesis. We propose to study the effects of HRV on sphingolipid synthesis in children with asthma and airway epithelial cells. These studies could then further solidify the central role of sphingolipids in asthma pathogenesis that has been predicted by the commonality and the strong association of 17q21 genotypes to asthma. Two specific aims are proposed to assess the overall hypothesis that the sphingolipid de novo synthesis pathway is critical not only for asthma pathogenesis but also in response to the most common trigger for asthma attacks. In Aim 1, we will determine sphingolipid synthesis in the respiratory tract in children with asthma and HRV infection. Sphingolipids will be assessed in nasal fluid, blood, and gene expression in nasal cells obtained from children during and after the resolution of HRV-triggered asthma attacks. In a subaim, we will evaluate the effects of HRV on sphingolipid metabolism and gene expression in primary human airway epithelial cells (HAEC) with homozygous for a common 17q21 asthma variation that leads to decreased blood sphingolipids in children with asthma. HAEC from an established biorepository from adult donors and nasal brushings from children all grown at air-liquid interface will be infected with HRV and RSV and evaluated for effects on sphingolipid synthesis. For Aim 2, we will test the hypothesis that the altered ratio of the sphingolipid mediator sphingosine 1-phosphate and sphinganine 1 phosphate, which we found in SPT deficiency and children with the 17q21 asthma risk genotypes, leads to airway hyperreactivity. Overall, these studies not only inform on the role of sphingolipids in the pathogenesis of asthma and the relation to its most common trigger but may lead to new therapeutic approaches involving sphingolipid metabolism.