Lung Epithelial-Immune Interactions In Respiratory Virus Infection

 描述（由申请方提供）：呼吸道合胞病毒（RSV）感染可导致婴儿严重细支气管炎和肺炎，是新生儿和婴儿住院的主要原因。然而，RSV在其他健康成人中通常控制良好。气道上皮细胞（AEC）构成RSV感染的主要靶标。上皮细胞通过分泌I型干扰素（IFN α/IFN β）促进干扰素刺激基因（ISGs）的表达，在抗病毒宿主防御中发挥重要作用。ISG在抑制病毒复制中起关键作用。干扰素刺激还导致上皮细胞产生趋化因子（例如CXCL 10），这些趋化因子招募白细胞以消除病毒。我们和其他人已经表明，特定的生长因子和细胞因子，如KGF和IL-22具有上皮保护功能。这些因子的一个重要来源是α δ T细胞。IL-22由γ δ T细胞产生，为肺和肠上皮细胞提供粘膜屏障功能。据信，γ δ T细胞的主要功能是新生儿保护。先前发表的人类数据和我们自己的小鼠数据显示，在生命早期RSV感染后，IL-22+ β δ T细胞严重丧失。因此，在生命早期，上皮细胞和T细胞功能的不足可预期在RSV感染期间引起更严重的疾病。在初步研究中，通过RNA-seq分析确定，RSV感染人AEC诱导了几种基因，在多种ISG（包括OASL）中观察到最高水平的应答。最近显示OASL抑制RSV在上皮细胞系中的复制。感染诱导的粘蛋白基因的表达被IL- 22抑制，而ZO-1样紧密连接蛋白的表达减少被阻止。在与rIL- 22孵育后，在人AEC中观察到对病毒复制的显著抑制。在小鼠研究中，RSV感染导致产生IL-22的α δ T细胞的急剧损失，特别是在幼年小鼠中。与来自年长小鼠的AEC相比，RSV从幼年小鼠的AEC诱导较弱的CXCL 10应答。总的来说，这些观察结果促使我们假设，在生命早期对RSV诱导的疾病的易感性是由于上皮细胞和先天性免疫缺陷导致的。 免疫抗病毒防御反应削弱宿主对RSV有效防御。为了证明我们的假设，我们将：目标1。研究T细胞及其介导因子IL-22在RSV感染保护中的作用。目标2.表征在存在或不存在IL-22的情况下在RSV感染的人气道上皮细胞和小鼠体内诱导的抗病毒防御机制。目标3：确定RSV感染导致幼年小鼠中γ δ T细胞数量减少和这些细胞产生IL-22的机制。在完成拟议的研究后，我们期望更好地了解先天免疫系统和保护宿主免受RSV感染的气道上皮细胞之间的相互作用。

 DESCRIPTION (provided by applicant): Respiratory syncytial virus (RSV) infection can cause severe bronchiolitis and pneumonia in infants and is the primary cause of hospitalization in newborns and infants. However, RSV is generally well-controlled in otherwise healthy adults. Airway epithelial cells (AECs) constitute the primary target of RSV infection. Epithelial cells pla an important role in antiviral host defense by secreting type I (IFN α/ß) interferons that in tur promote expression of interferon-stimulated genes (ISGs). ISGs play a critical role in inhibiting viral replication. IFN-stimulation also causes the production of chemokines such as CXCL10 from epithelial cells that recruit leukocytes to eliminate the virus. We and others have shown that specific growth factors and cytokines such as KGF and IL-22 have epithelial-protective functions. An important source of these factors is the ɣδ T cell. IL-22 produced by ɣδ T cells affords mucosal barrier function for lung and intestinal epithelial cells. It is believed that the primary function of ɣδ T cells is neonatal protection. Previously published human data and our own mouse data show severe loss of IL-22+ɣδ T cells upon RSV infection in early life. Thus, inadequacy of epithelial and ɣδ T cell function in early life can be expected to cause more severe disease during RSV infection. In preliminary studies, RSV infection of human AECs induced several genes with the highest level of response observed for multiple ISGs, including OASL, as determined by RNA-seq analysis. OASL was recently shown to inhibit RSV replication in epithelial cell lines. Expression of infection-induced mucin gene was inhibited by IL- 22 while decrease in expression of a ZO-1-like tight junction protein was prevented. Upon incubation with rIL- 22 a striking inhibition of viral replication was observed in the human AECs. In mouse studies, RSV infection resulted in a drastic loss of IL-22-producing ɣδ T cells, especially in infant mice. RSV induced a weaker CXCL10 response from AECs of infant mice as compared to that from older mice. Collectively, these observations prompt us to hypothesize that the susceptibility to RSV-induced disease in early life is due to inadequate epithelial cell and innate immune antiviral defense response that impair effective host defense against RSV. To prove our hypothesis, we will: Aim 1. Investigate the role of ɣδ T cells and its mediator IL-22 in protectin from RSV infection. Aim 2. Characterize anti-viral defense mechanisms that are induced in RSV-infected human airway epithelial cells and in vivo in mice in the presence or absence of IL-22. Aim 3. Determine the mechanism by which RSV infection results in reduced numbers of ɣδ T cells and IL-22 production by these cells in infant mice. After completion of the proposed studies, we expect to gain a better understanding of interactions between the innate immune system and airway epithelial cells that protect the host from RSV infection.