Antiviral Innate Pathways and Superoxide Dismutase in RSV Bronchiolitis

描述(申请人提供)：呼吸道合胞病毒(RSV)是引起儿童急性下呼吸道感染(毛细支气管炎)的单一最重要的病毒病原体。目前还没有疫苗或特定疗法被批准用于预防和治疗RSV感染。 暴露于环境烟草烟雾(ETS)已被确定为严重RSV感染的危险因素，但决定ETS和感染并存的机制在很大程度上尚不清楚。最近的研究支持这样的观点，即临床疾病的严重性是由呼吸道中更高水平的RSV复制驱动的，我们小组的研究表明，患有RSV毛细支气管炎严重发作的婴儿呼吸道中超氧化物歧化酶(SOD)抗氧化酶的表达和活性显著降低，特别是在婴儿接触ETS的情况下。令人惊讶的是，我们新的初步数据表明，SOD酶能够抑制培养的上皮细胞和实验感染的小鼠中RSV的复制。我们提出了一个新的假设，即肺中的SOD酶通过限制RSV的复制和缩短病毒的脱落，作为宿主抗病毒基因产物具有以前未被认识的功能。我们的第二个假设是，在接触ETS的RSV感染者中，这些酶的表达和抗病毒功能减少/受损。在这个探索性的项目中，我们建议通过两个特定的目标来检验这些假设。在目标1中，将分析不同临床严重程度的呼吸道合胞病毒感染婴儿鼻咽分泌物(NPS)中SOD蛋白的分布、相对丰度和活性，以及是否接触ETS。超氧化物歧化酶水平和活性将与核动力源中RSV的浓度(即病毒滴度/载量)相关。在目标2中，我们将检验特定的假设，即肺中超氧化物歧化酶活性的增加将钝化RSV的复制并改善呼吸道疾病。为此，我们将通过腺相关病毒(AAV)介导的基因转移或使用基于Salen的EUK SOD模拟物来增加肺中SOD的表达，并在RSV感染和共同暴露于ETS的实验小鼠模型中测量RSV滴度(作为主要终点)。超氧化物歧化酶的保护作用将通过检测临床疾病、肺部炎症/病理和病毒介导的呼吸道高反应性来评估。该项目可能通过提出新的更积极的战略来治疗高危婴儿(即暴露于ETS的婴儿)的原发呼吸道病毒感染，从而可能具有重要的翻译意义。这些治疗机会将在这个探索性项目的结果的基础上在未来的R01应用中进行探索。

DESCRIPTION (provided by applicant): Respiratory syncytial virus (RSV) is the single most important viral pathogen causing acute lower respiratory- tract infections (bronchiolitis) in children. No vaccine or specific therapy is currently licensed to prevent and treat RSV infections. Exposure to environmental tobacco smoke (ETS) has been identified as a risk factor for the development of severe RSV infections, yet the mechanisms that determine ETS and infection co-morbidity are largely unknown. Recent studies support the notion that severity of clinical disease is driven by higher level of RSV replication in the airways and studies by our group have shown that expression and activity of superoxide dismutase (SOD) antioxidant enzymes are significantly decreased in the airways of infants with severe episodes of RSV bronchiolitis, particularly if infants had been exposed to ETS. Surprisingly, our new preliminary data have shown that SOD enzymes are able to inhibit RSV replication in cultured epithelial cells and in experimentally-infected mice. We propose the novel hypothesis that lung SOD enzymes have a previously unrecognized function as host antiviral gene products by limiting RSV replication and shortening viral shedding. Our secondary hypothesis is that expression and antiviral function of such enzymes are reduced/impaired in RSV-infected subjects who are exposed to ETS. In this exploratory project we propose to test these hypotheses by two Specific Aims. In Aim 1, the profile, relative abundance, and activity of SOD proteins will be analyzed in nasopharyngeal secretions (NPS) of infants with RSV infections of different clinical severity and with or without exposure to ETS. SOD levels and activity will be correlated with the concentration (i.e. viral titer/load) of RSV in NPS. In Aim 2, we will test the specific hypothesis that increasing of SOD activity in the lungs will blunt RSV replication and improve airway disease. For that, we will increase SOD expression in the lung by adeno-associated virus (AAV)-mediated gene transfer or by the use of salen-based EUK SOD mimetics, and measure RSV titer (as the main endpoint) in an experimental mouse model of RSV infection and co-exposure to ETS. The protective effect of SOD will be evaluated by examining clinical disease, lung inflammation/pathology, and viral-mediated airway hyperresponsiveness. This project may have important translational implications by suggesting new and more aggressive strategies to treat primary respiratory viral infections in high risk infants (i.e. those exposed to ETS). These therapeutic opportunities will b explored in a future R01 application based on the results of this exploratory project.