Roles of IL-17-induced gene expression in airway epithelial host defense

描述（由申请人提供）：在上一个资助期间，我们的实验室发现了IL- 17A/F对人和小鼠气道上皮细胞中DEFB4（以前称为2-防御素2）或mBD3/4（小鼠相当于DEFB4）， CCL20和IL-19的刺激。已知DEFB4或mBD3/4和CCL20都具有抗微生物活性，它们也是将表达ccr6的细胞（如Th17和未成熟树突状细胞）募集到气道管腔的主要配体。因此，存在自分泌/旁分泌机制调节气道黏膜IL-17A/F及其产生细胞的升高和/或维持。我们最近的研究结果表明，IL-17A/F-诱导IL-19 （IL-10细胞因子家族成员）也刺激DEFB4和mBD3/4的体外表达。因此，通过IL-17A/ f诱导的气道上皮基因表达，Th17细胞进入气道管腔增强抗微生物活性并募集到宿主防御存在内在机制。更新申请将重点关注IL-17A/ f靶向上皮基因在宿主防御机制中的作用。具体来说，我们假设IL-17A/ f诱导的气道上皮基因产物在架起先天和适应性宿主防御呼吸道细菌感染的桥梁中起着非常重要的作用。为了验证这一假设，将使用已建立的肺炎克雷伯菌和临床相关的铜绿假单胞菌感染小鼠模型。提出了两个具体目标。特异性目的1是测试IL-17A和/或IL-17F是否参与启动气道上皮宿主先天防御肽CCL20和/或mBD3/4的产生，以对抗感染气道中的细菌感染。具体而言，我们将进行详细的时间过程研究，以建立IL-17细胞因子的存在与上皮细胞CCL20和mBD3/4的表达以及细菌感染后小鼠气道中细菌清除之间的联系（Aim 1A）。随后将对基因缺失小鼠进行研究，以确定IL-17细胞因子及其受体信号是否在CCL20和mBD3/4诱导和随后的细菌杀死/清除（Aim 1B）中是必需的。目的1C是确定IL-17细胞因子诱导的上皮CCL20和mBD3/4是否对细菌清除至关重要。在Specific Aim 2中，我们将重点关注IL-17诱导的上皮CCL20在细菌感染后Th17细胞向气道募集中的机制。具体来说，我们将讨论上皮细胞CCL20表达和Th17细胞募集是否存在时间过程相关性（Aim 2A）。接下来的研究将证明CCL20在将Th17细胞募集到细菌感染的气道中的功能（Aim 2B）。使用过继性转移方法，我们将确定CCL20/CCR6+轴是否参与Th17细胞向气道的募集（Aim 2C）。这些研究将阐明il -17诱导的上皮细胞CCL20和mBD3/4在启动先天和适应性阶段上皮宿主防御以对抗气道细菌感染中的作用。

DESCRIPTION (provided by applicant): During the last grant period, our lab has uncovered the stimulation of DEFB4 (previously called 2-defensin 2) or mBD3/4 (mouse equivalent to DEFB4), CCL20, and IL-19 in human and mouse airway epithelial cells by IL- 17A/F. Both DEFB4 or mBD3/4, and CCL20 are known to have anti-microbial activity and they are also the primary ligands for the recruitment of CCR6-expressing cells, such as Th17 and immature dendritic cells, to the airway lumen. Thus, there is an autocrine/paracrine mechanism to regulate the elevation and/or maintenance of IL-17A/F and their producing cells in airway mucosa. Our recent findings demonstrated that IL-17A/F- induced IL-19, a member of IL-10 cytokine family, also stimulates DEFB4 and mBD3/4 expression in vitro. Thus, there is a built-in mechanism in reinforcing the anti-microbial activity and recruitment of Th17 cells to the airway lumen for host defense through IL-17A/F-induced expression of airway epithelial genes. The renewal application will focus on the roles of IL-17A/F-targeted epithelial genes in host defense mechanism. Specifically, we hypothesize that IL-17A/F-induced airway epithelial gene products play very essential roles in bridging the innate and adaptive host defense responses to against bacterial infection in airways. To test this hypothesis, the well-established Klebsiella pneumoniae and the clinically relevant Pseudomonas aeruginosa infection mouse models will be used. Two Specific Aims are proposed. Specific aim 1 is to test whether or not IL-17A and/or IL-17F are involved in initiating the production of airway epithelial host innate defense peptides, CCL20 and/or mBD3/4, to combat bacterial infection in infected airways. Specifically, we will carry out a detailed time-course study to establish such a connection between the presence of IL-17 cytokines and the expression of epithelial CCL20 and mBD3/4, and the bacterial clearance in mouse airways after bacterial infection (Aim 1A). This will be followed by the study on genetic null mice to see if IL-17 cytokines and their receptor signaling are required in CCL20 and mBD3/4 induction and subsequent bacterial killing/clearance (Aim 1B). Aim 1C is to address if epithelial CCL20 and mBD3/4 induced by IL-17 cytokines are essential for bacterial clearance or not. For Specific Aim 2, we will focus on the mechanism of IL-17- induced epithelial CCL20 in Th17 cell recruitment to the airways after bacterial infection. Specifically, we will address if there is a time-course correlation on the expression of epithelial CCL20 and Th17 cell recruitment (Aim 2A). This will be followed by the study to demonstrate the function of CCL20 in the recruitment of Th17 cells to the bacterial infected airways (Aim 2B). Using an adoptive transfer approach, we will address if a CCL20/CCR6+ axis is involved in Th17 cell recruitment to the airways (Aim 2C). These studies will illustrate the roles of IL-17-induced epithelial CCL20 and mBD3/4 in initiating both innate and adaptive phases of epithelial host defense to combat bacterial infection in the airways. PUBLIC HEALTH RELEVANCE: Airway epithelial cells are primary targets of bacterial infection. To combat the infection, airway epithelial cells are responsible for the calls of both innate and adaptive host defense mechanisms. The goal of the renewal application is to examine the roles of these innate molecules, CCL20 and mBD3/4, in mouse models after Klebsiella pneumoniae and Pseudomonas aeruginosa infections, using various genetic knockout and transgenic approaches. Such a study will lead to a better understanding of host anti-microbial mechanism that may lead to the development of new therapeutic treatment of bacterial infection in the airways.