Mechanisms of age-specific differences in the Type I IFN response to respiratory viral infection

项目总结/摘要 呼吸道病毒感染是全球婴儿死亡的主要原因， 新生儿在所有12个月以下的婴儿死于呼吸道病毒感染的病例中， 妊娠30周前出生的新生儿。直到最近，大多数关于新生儿和婴儿原发性 对病毒感染的免疫应答是基于来自推广到新生儿的成年动物模型的数据。 目前的数据表明，一个更相关的模型，为人类婴儿是新生小鼠，因为一个 出生后免疫系统的类似进化。我们建立了一个3日龄的小鼠模型， 流感病毒感染，与晚期早产（妊娠34-37周）人类新生儿相当。以确定 我们通过Nanostring技术测量了对流感病毒初始先天反应的年龄特异性差异 新生儿和成人全肺12小时诱导的753个免疫相关基因的RNA转录变化 PR 8流感病毒感染后和未感染的年龄匹配的新生儿。感染后12小时， 新生小鼠与未感染的年龄匹配小鼠具有相似的转录谱，而 感染的成年小鼠上调了数百个基因，特别是在I型干扰素（IFN）途径中， 抗病毒防御的重要组成部分。虽然I型IFN诱导关键的抗病毒途径，但IFN也可以 有助于放大促炎反应，这会增加成人呼吸道的损伤。 然而，婴儿特异性I型干扰素动力学和I型干扰素是否对婴儿是保护性的或有害的， 这是一个巨大的知识差距。在初步研究中，缺乏I型IFN受体的新生小鼠 (IFNαβR-/-）在流感病毒感染后的存活率为80%， C57 BL/6的存活率仅为15%。这与成年小鼠正好相反，成年小鼠的病毒感染更多， 在没有I型IFN应答的情况下是致病性的。我们假设新生儿患有异常的I型 IFN对流感病毒的反应动力学直接导致氧化应激、炎症和肺组织 损害由于IFNαβ受体的存在在成人中具有保护作用，我们还假设， 新生儿IFNαβ受体依赖性应答可能涉及与成人I型IFN α β受体依赖性应答不同的下游途径 IFN应答。为了验证这一假设，我们建议调查婴儿的发育差异， 通过下一代测序的强大组合， 新生小鼠感染模型和创新的原代新生儿肺上皮细胞培养。体内关键 将在新生儿和成人、初治和流感感染、C57 BL/6和C57 BL/6中确定转录组差异。 IFNαβR-/- FACS纯化的鼠肺II型上皮细胞。我们还将定义年龄特异性I型IFN动力学 促进新生儿流感感染肺上皮细胞氧化应激反应的差异 这有助于致病性。最后，我们将测试抗氧化剂（N-乙酰半胱氨酸）是否是合理的 在这一极其脆弱的人群中治疗婴儿呼吸道病毒感染的治疗选择。

Project Summary/Abstract Respiratory viral infections contribute substantially to global infant losses and disproportionately affect preterm neonates. Of all deaths less than 12 months of age secondary to a respiratory viral infection, 55% occur in a neonate born before 30 weeks gestation. Until recently, most research about neonatal and infant primary immune response to viral infections was based on data from adult animal models generalized to the neonate. Current data suggest that a more relevant model for the human infant is the neonatal mouse because of a similar evolution of the immune system post-birth. We have established a 3-day old murine model of infant influenza virus infection, comparable to a late preterm (34-37 weeks gestation) human neonate. To determine age-specific differences in the initial innate response to influenza virus, we measured by Nanostring technology RNA transcriptional changes in 753 immune-related genes induced in neonatal and adult whole lungs 12 hours after PR8 influenza virus infection and uninfected age-matched neonates. Twelve hours after infection, the neonatal mouse had a similar transcriptional profile to an uninfected age-matched mouse, whereas the infected adult mouse upregulated hundreds of genes, especially in the type I interferon (IFN) pathway, an essential component of antiviral defense. Although type I IFNs induce key antiviral pathways, IFNs can also serve to amplify proinflammatory responses, which can increase damage in the respiratory tract in adults. However, the infant-specific type I IFN kinetic and whether type I IFNs are protective or deleterious to infants represents a significant knowledge gap. In preliminary studies, neonatal mice devoid of the type I IFN receptor (IFNαβR-/-) had a greatly improved survival rate of 80% after influenza virus infection, compared to the C57BL/6 survival rate of only 15%. This is in direct opposition to adult mice, where viral infection is more pathogenic in the absence of a type I IFN response. We hypothesize that the neonate has an aberrant type I IFN kinetic in response to influenza virus which directly leads to oxidative stress, inflammation and lung tissue damage. Since the presence of IFNαβ receptor is protective in adults, we also hypothesize that differences in neonatal IFNαβ receptor-dependent responses may involve distinct downstream pathways than the adult type I IFN response. To test this hypothesis, we propose to investigate developmental differences in the infant response to respiratory viral infection through a powerful combination of next generation sequencing, an in vivo neonatal mouse infection model and an innovative primary neonatal lung epithelial cell culture. Key in vivo transcriptome differences will be determined in neonatal and adult, naïve and influenza-infected, C57BL/6 and IFNαβR-/- FACS purified murine lung Type II epithelial cells. We will also define age-specific type I IFN kinetic differences which promote an oxidative stress response in neonatal influenza-infected lung epithelial cells which contributes to pathogenicity. Finally, we will test if an anti-oxidant (N-acetyl cysteine) is a reasonable therapeutic option to treat infant respiratory viral infection in this extremely vulnerable population.