Early Life Rhinovirus Infection and Childhood Asthma

项目摘要 出生队列研究发现，早期喘息与呼吸相关的显著关联 13岁以下儿童的呼吸道感染和哮喘的发展。这些研究表明 早期呼吸道感染对肺部和/或免疫细胞发育有直接影响，并有发生 哮喘。为了确定可能的机制，我们建立了早期轮状病毒感染的小鼠模型。感染 6天龄小鼠，但不是成熟小鼠，诱导持久的粘液化生，嗜酸性炎症和 呼吸道高反应性(AHR)与2型固有淋巴样细胞(ILC2)的扩张和 依赖IL-13、IL-25和IL-33。对于这次续签申请，我们已经开发了初步数据 表明早期轮状病毒感染增加了呼吸道IL-25+DCLK1+刷状细胞的数量，提供了 持续性ILC2依赖哮喘样表型的机制。此外，我们还发现，在 未成熟小鼠、NLRP3炎症体激活和IL-1β成熟抑制2型细胞因子 表达和粘液化生。在这项建议中，我们将检验一般假设，即在早期- LIFE轮状病毒感染、ILC2依赖型2型气道炎和粘液化生的发生 代表簇状细胞RV诱导的IL-25信号(促进表型)和NLRP3- 依赖的IL-1β信号(抑制表型)。为了测试这一点，我们提出了以下目标： 具体目标1.确定呼吸道刷状细胞(Tuft)在病毒诱导的IL-25中的作用 制作。我们假设：1)早期轮状病毒感染刺激了轮状病毒数量的持续增加 产生IL-25的气道绒毛细胞；2)绒毛细胞是RV诱导的ILC2扩张、粘液化生所必需的 3)RV诱导的IL-25和IL-13的产生(由ILC2和M2极化的巨噬细胞)构成 丛生细胞发育的前馈机制。 特定目的2.确定IL-1β在轮状病毒诱导的粘液化生中的作用 和AHR。我们的假设是：1)在未成熟小鼠中，RV诱导的NLRP3炎症体依赖的IL-1β 产生抑制哮喘样表型；2)IL-1β抑制上皮细胞固有细胞因子表达； (3)脂多糖和家犬粉尘均可抑制黏液化生表型的形成。 通过刺激炎性小体的启动和激活。 具体目标3.确定早期RV-C感染的影响。我们假设：1)比较 对于RV-A，6日龄小鼠感染RV-C可诱发更多的II型炎症、粘膜化生和AHR；2) RV-C诱导丛状细胞更大的扩张；3)RV-C引起炎性小体启动而不是激活，从而 允许更多和更持久的2型细胞因子表达和粘液化生。 将对患有呼吸道病毒感染的未成熟小鼠和婴儿进行研究。完成拟议的工作 将为哮喘的发病机制提供新的见解，并为预防提供新的靶点。

Project Summary Birth cohort studies have found significant associations between early-life wheezing-associated respiratory tract infections and the development of asthma in children up to 13 years of age. These studies suggest that early life respiratory tract infections have a direct effect on lung and/or immune cell development and the risk of asthma. To determine possible mechanisms, we established a mouse model of early-life RV infection. Infection of 6 day-old mice, but not mature mice, induces long-lasting mucous metaplasia, eosinophilic inflammation and airways hyperresponsiveness (AHR) which is associated with type 2 innate lymphoid cell (ILC2) expansion and dependent on IL-13, IL-25 and IL-33. For this renewal application, we have developed preliminary data showing that early-life RV infection increases the number of airway IL-25+ DCLK1+ brush cells, providing a mechanism for a persistent ILC2-dependent asthma-like phenotype. In addition, we have found that, in immature mice, activation of the NLRP3 inflammasome and IL-1β maturation inhibits type 2 cytokine expression and mucous metaplasia. In this proposal, we will test the general hypothesis that, following early- life RV infection, development of ILC2-dependent type 2 airway inflammation and mucous metaplasia represents a balance between tuft cell RV-induced IL-25 signaling (promotes the phenotype) and NLRP3- dependent IL-1β signaling (suppresses the phenotype). To test this, we propose the following Aims: Specific Aim 1. Determine the contribution of airway brush (tuft) cells to viral-induced IL-25 production. We hypothesize that: 1) early-life RV infection stimulates a persistent increase in the number of IL-25-producing airway tuft cells; 2) tuft cells are required for RV-induced ILC2 expansion, mucous metaplasia and AHR; 3) RV-induced IL-25 and IL-13 production (by ILC2s and M2 polarized macrophages) constitute a feed-forward mechanism for tuft cell development. Specific Aim 2. Determine the role of IL-1β on the development of RV-induced mucous metaplasia and AHR. We hypothesize that: 1) in immature mice, RV-induced, NLRP3 inflammasome-dependent IL-1β production suppresses the asthma-like phenotype; 2) IL-1β inhibits epithelial cell innate cytokine expression; and 3) LPS and dog-associated house dust each attenuate development of the mucous metaplasia phenotype by stimulating inflammasome priming and activation. Specific Aim 3. Determine the effects of early-life RV-C infection. We hypothesize that: 1) compared to RV-A, RV-C infection of 6 day-old mice induces more type 2 inflammation, mucous metaplasia and AHR; 2) RV-C induces greater expansion of tuft cells; 3) RV-C elicits inflammasome priming but not activation, thereby permitting greater and more long-lasting type 2 cytokine expression and mucous metaplasia. Immature mice and infants with respiratory viral infections will be studied. Completion of the proposed work will provide new insight into the pathogenesis of asthma development, and identify new targets for prevention.