Early Life Rhinovirus Infection and Childhood Asthma

 描述（由申请方提供）：在高危婴儿中，与鼻病毒（RV）相关的喘息性疾病是哮喘发展的重要风险因素。因此，生命早期的RV感染与其他因素（如遗传背景、过敏原暴露和微生物组）结合可能会调节免疫应答，增加哮喘发展的可能性。为了测试这一点，我们开发了一种RV 1B感染的未成熟小鼠模型。与成熟动物相反，用RV 1B感染的6日龄小鼠发展出持续的气道高反应性、粘膜Meta和IL-13产生。这种哮喘样表型依赖于产生IL-13的2型先天淋巴细胞（ILC 2）的群体。在本研究中，我们将检验以下一般假设：在易感个体中，早期RV感染通过产生IL-13的ILC 2的扩增促进儿童哮喘的发展。为了检验这一一般假设，提出了三个具体目标：目标1。确定IL-25、IL-33和TSLP在RV诱导的新生BALB/c小鼠粘膜化生和气道高反应性中的作用。我们假设，在未成熟的6日龄小鼠中：i）RV感染增加气道细胞产生IL-33和TSLP;（ii）IL-25、IL-33和TSLP是最大粘膜化生和AHR所需的;（iii）IFN-γ应答缺陷允许RV诱导的TSLP产生;和iv）IL-25启动子处存在容许的表观遗传状态，允许RV诱导的转录。目标二。确定ILC 2对RV诱导的气道反应的贡献。我们假设：i）在RV感染的未成熟小鼠中，IL-25、IL-33和TSLP协同作用以调节ILC 2的扩增和IL-13产生; ii）ILC 2是最大RV诱导的2型细胞因子表达、粘膜化生和AHR所需的且足够的;和iii）IFN-γ减弱ILC 2扩增和IL-13产生。目标3。确定新生儿RV感染对随后异源再感染反应的影响。我们假设：i）早期RV 1B感染改变了对随后的RV 2或RSV感染的免疫应答，导致2型而不是1型应答; ii）协同的2型应答由ILC 2驱动;和iii）RV直接刺激离体ILC 2产生IL-13。对于目的1-3，为了确定ILC 2是否构成对生命早期呼吸道病毒感染的常见细胞应答，我们将比较6日龄未成熟小鼠和8月龄成熟小鼠中的RV 1B、RV 2和RSV-A感染。此外，为了支持目标1和2，我们将分析从急性呼吸道病毒感染住院婴儿中采集的鼻和气管灌洗液样本中的IL-25、IL-33和IL-33水平以及ILC 2。最后，为了开始理解为什么只有一些暴露于早期病毒感染的婴儿可能发展为哮喘，我们将在RV感染的A/J、C57 BL/6和无菌小鼠中进行“概念验证”实验，检查粘液化生、气道高反应性和ILC 2。

 DESCRIPTION (provided by applicant): In high risk infants, wheezing-associated illness with rhinovirus (RV) is a significant risk factor for asthma development. Thus, RV infection in early life, in combination with other factors such as genetic background, al- lergen exposure and microbiome, may modulate the immune response, increasing the likelihood of asthma development. To test this, we developed an immature mouse model of RV1B infection. In contrast to mature animals, 6 day-old mice infected with RV1B develop sustained airways hyperresponsiveness, mucous meta- plasia and IL-13 production. This asthma-like phenotype is dependent a population of IL-13-producing type 2 innate lymphoid cells (ILC2s). In this proposal, we will test the general hypothesis that, in susceptible individual- als, early-life RV infection contributes to childhood asthma development via the expansion of IL-13-producing ILC2s. To test this general hypothesis, three specific aims are proposed: Aim 1. Determine the roles of IL-25, IL-33 and TSLP in RV-induced mucous metaplasia and airways hyperresponsiveness in neonatal BALB/c mice. We hypothesize that, in immature 6 day-old mice: i) RV infection increases airway cell production of IL-33 and TSLP; (ii) IL-25, IL-33 and TSLP are required for maxi- mal mucous metaplasia and AHR; (iii) a deficient IFN-γ response allows RV-induced TSLP production; and iv) a permissive epigenetic state exists at the IL-25 promoter, allowing RV-induced transcription. Aim 2. Determine the contribution of ILC2s to RV-induced airway responses. We hypothesize that: i) in RV-infected immature mice, IL-25, IL-33 and TSLP function cooperatively to regulate expansion and IL-13 production by ILC2s; ii) ILC2s are required and sufficient for maximal RV-induced type 2 cytokine expression, mucous metaplasia and AHR; and iii) IFN-γ attenuates ILC2 expansion and IL-13 production. Aim 3. Determine the effects of neonatal RV infection on responses to subsequent heterologous re- infection. We hypothesize that: i) early-life RV1B infection alters the immune response to subsequent RV2 or RSV infection, leading to type 2 rather than type 1 responses; ii) synergistic type 2 responses are driven by ILC2s; and iii) RV directly stimulates IL-13 production from ILC2s ex vivo. For Aims 1-3, to determine whether ILC2s constitute a common cellular response to early-life respiratory viral infection, we will compare RV1B, RV2 and RSV-A infections in 6 day-old immature mice and 8 month-old mature mice. Also, to support Aims 1 and 2, we will analyze IL-25, IL-33 and IL-33 levels and ILC2s in nasal and tracheal lavage samples taken from infants hospitalized with acute respiratory viral infections. Finally, to begin to understand why only some infants exposed to early-life viral infection may develop asthma, we will perform "proof-of-concept" experiments examining mucous metaplasia, airways hyperresponsiveness and ILC2s in RV-infected A/J, C57BL/6 and germ-free mice.