Early Life Rhinovirus Infection and Childhood Asthma

 描述(由申请人提供)：在高危婴儿中，与鼻病毒(RV)喘息相关的疾病是哮喘发生的重要风险因素。因此，生命早期的RV感染，与遗传背景、过敏原暴露和微生物群等其他因素相结合，可能调节免疫反应，增加哮喘发生的可能性。为了测试这一点，我们开发了一种未成熟的RV1B感染小鼠模型。与成熟动物相比，感染RV1B的6日龄小鼠出现持续的呼吸道高反应性、粘液化生和IL-13产生。这种哮喘样的表型依赖于一群产生IL-13的2型先天性淋巴样细胞(ILC2s)。在这项提案中，我们将检验一个普遍的假设，即在易感个体ALS中，早期RV感染通过扩大产生IL-13的ILC2而促进儿童哮喘的发展。为了验证这一普遍假设，提出了三个特定的目标：目的1.确定IL-25、IL-33和TSLP在轮状病毒诱导的BALB/c新生小鼠粘膜化生和呼吸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)轮状病毒感染增加了呼吸道细胞产生IL-33和TSLP；(Ii)IL-25、IL-33和TSLP是最大粘膜化生和急性呼吸道高反应所必需的；(Iii)干扰素-γ反应缺陷允许轮状病毒诱导TSLP的产生；以及iv)IL-25启动子存在允许的表观遗传状态，允许RV诱导转录。目的2.确定ILC2在RV诱导的呼吸道反应中的作用。我们假设：在RV感染的未成熟小鼠中，IL-25、IL-33和TSLP协同作用调节ILC2的扩张和IL-13的产生；ii)ILC2是最大限度地表达RV诱导的2型细胞因子、粘液化生和AHR所必需的且充分的；以及iii)干扰素-γ抑制ILC2的扩张和IL-13的产生。目的3.确定新生儿轮状病毒感染对随后异种再感染反应的影响。我们假设：i)早期RV1B感染改变了对随后的RV2或RSV感染的免疫反应，导致了2型而不是1型反应；ii)协同的2型反应是由ILC2s驱动的；iii)RV直接刺激ILC2s在体外产生IL-13。对于AIMS 1-3，为了确定ILC2是否构成对早期呼吸道病毒感染的常见细胞反应，我们将比较6天龄未成熟小鼠和8个月龄成熟小鼠的RV1B、RV2和RSV-A感染。此外，为了支持目标1和目标2，我们将分析急性呼吸道病毒感染住院婴儿的鼻腔和气管冲洗液样本中的IL-25、IL-33和IL-33水平以及ILC2。最后，为了开始了解为什么只有一些早期接触病毒感染的婴儿可能会患上哮喘，我们将在感染RV的A/J、C57BL/6和无菌小鼠身上进行“概念验证”实验，检测粘液化生、呼吸道高反应性和ILC2。

 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.