Lung Epithelial-Immune Interactions In Respiratory Virus Infection

 描述(申请人提供)：呼吸道合胞病毒(RSV)感染可导致婴儿严重的毛细支气管炎和肺炎，是新生儿和婴儿住院的主要原因。然而，在其他健康的成年人中，RSV通常得到很好的控制。呼吸道上皮细胞(AECs)是呼吸道合胞病毒感染的主要靶点。上皮细胞通过分泌I型干扰素(干扰素α/B)促进干扰素刺激基因的表达，在抗病毒宿主防御中发挥重要作用。ISGS在抑制病毒复制方面起着关键作用。刺激干扰素还会导致上皮细胞产生趋化因子，如CXCL10，这些细胞招募白细胞来清除病毒。我们和其他人已经证明，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。这些因素的一个重要来源是ɣδT细胞。ɣδT细胞产生的IL-22为肺和肠上皮细胞提供粘膜屏障功能。目前认为ɣδT细胞的主要功能是保护新生儿。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，呼吸道合胞病毒感染会导致IL-22+ɣδT细胞严重丧失。因此，在呼吸道合胞病毒感染过程中，早期生命中上皮细胞和ɣδT细胞功能不足可能会导致更严重的疾病。在初步研究中，RSV感染人血管内皮细胞诱导了几个基因，通过RNA-seq分析确定，这些基因对包括OASL在内的多个ISG的反应水平最高。OASL最近被证明能抑制RSV在上皮细胞系中的复制。IL-22抑制感染诱导的粘蛋白基因的表达，同时阻止ZO-1样紧密连接蛋白的表达减少。人血管内皮细胞与rIL-22孵育后，病毒复制受到显着抑制。在小鼠研究中，呼吸道合胞病毒感染导致产生IL-22的ɣδT细胞急剧丧失，特别是在幼鼠身上。与老年小鼠相比，RSV诱导幼鼠AECs产生的CXCL10反应较弱。总而言之，这些观察结果促使我们假设，早期生命对RSV诱导的疾病的易感性是由于上皮细胞不足和先天的 免疫抗病毒防御反应，损害对RSV的有效宿主防御。为了验证我们的假设，我们将：目的1.研究ɣδT细胞及其介体IL-22在呼吸道合胞病毒感染中的保护作用。目的2.研究呼吸道合胞病毒(RSV)感染的人呼吸道上皮细胞和体内存在或不存在IL-22的小鼠体内诱导的抗病毒防御机制。目的3.探讨呼吸道合胞病毒感染导致幼鼠ɣδT细胞数量减少及产生IL-22的机制。在完成拟议的研究后，我们希望更好地了解先天性免疫系统和保护宿主免受RSV感染的呼吸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.