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

项目总结 哮喘是遗传背景和环境之间复杂的相互作用造成的 触发点。17q21哮喘易感基因通过以下途径与儿童哮喘密切相关 ORMDL3.ORMDL3调节丝氨酸棕榈酰辅酶A转移酶(SPT)，该酶是 鞘磷脂的从头合成。我们证明了SPT活性的降低会导致 呼吸道高反应性。自那以后，越来越多的证据表明鞘脂新陈代谢 在呼吸道上皮细胞和ORMDL3相关哮喘动物模型中发生改变。我们有 最近的研究表明，哮喘儿童的鞘脂合成减少，特别是在 哮喘患者存在17q21等位基因。17q21基因型别也与患高血压的风险有关 在人类鼻病毒(HRV)呼吸道感染后发展为哮喘。这是相关的 因为心率变异性也是哮喘发作最常见的触发因素。 在小鼠和呼吸道上皮细胞中表现出强烈的初步数据支持 HRV感染与鞘磷脂水平及基因表达的相似性 缺乏，我们假设HRV感染可以进一步损害鞘磷脂的合成。我们 建议研究心率变异性对哮喘儿童鞘磷脂合成的影响 呼吸道上皮细胞。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，已被预测为共性和强相关性 17q21等位基因对哮喘的易感性。我们提出了两个具体的目标来评估整个假设 鞘磷脂从头合成途径不仅在哮喘发病机制中起着关键作用，而且在哮喘的发病机制中也起着重要作用。 也是为了应对哮喘发作的最常见触发因素。在目标1中，我们将确定 哮喘和HRV感染儿童呼吸道鞘磷脂的合成。 将评估鼻液、血液中的鞘磷脂和获得的鼻细胞中的基因表达。 在HRV引发的哮喘发作缓解期间和之后的儿童。在一个子目标中，我们 将评估心率变异性对神经鞘磷脂代谢和基因表达的影响 常见17q21哮喘变异的人呼吸道上皮细胞(HAEC) 这会导致哮喘儿童的血液鞘脂下降。HAEC来自一个成熟的 成人供体的生物库和儿童的鼻刷都是在气液中生长的 INTERFACE将感染HRV和RSV，并评估其对鞘磷脂合成的影响。 对于目标2，我们将检验以下假设：鞘磷脂介体的改变比率 1-磷酸鞘氨醇和1-磷酸鞘氨醇，我们在SPT缺乏症和 携带17q21哮喘高危基因的儿童，会导致呼吸道高反应性。总的来说，这些 研究不仅揭示了鞘磷脂在哮喘发病机制中的作用，而且 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.