Antiviral Innate Pathways and Superoxide Dismutase in RSV Bronchiolitis

描述（由申请方提供）：呼吸道合胞病毒（RSV）是引起儿童急性下呼吸道感染（细支气管炎）的最重要的病毒病原体。目前没有疫苗或特定疗法被许可用于预防和治疗RSV感染。 暴露于环境烟草烟雾（ETS）已被确定为严重RSV感染发展的风险因素，但决定ETS和感染共病的机制在很大程度上是未知的。最近的研究支持这样的观点，即临床疾病的严重程度是由气道中较高水平的RSV复制驱动的，并且我们小组的研究表明，在患有严重RSV细支气管炎发作的婴儿的气道中，超氧化物歧化酶（SOD）抗氧化酶的表达和活性显著降低，特别是如果婴儿暴露于ETS。令人惊讶的是，我们新的初步数据表明，SOD酶能够抑制RSV复制培养的上皮细胞和实验感染的小鼠。我们提出了一个新的假设，即肺SOD酶有一个以前未被认识到的功能，作为宿主抗病毒基因产物，通过限制RSV复制和缩短病毒脱落。我们的次要假设是，在暴露于ETS的RSV感染受试者中，这些酶的表达和抗病毒功能降低/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测试这些假设。在目标1中，将分析具有不同临床严重程度的RSV感染且暴露于或不暴露于ETS的婴儿的鼻咽分泌物（EHF）中SOD蛋白的谱、相对丰度和活性。SOD水平和活性将与RSV的浓度（即病毒滴度/载量）相关。在目标2中，我们将测试肺中SOD活性增加将减弱RSV复制并改善气道疾病的特定假设。为此，我们将通过腺相关病毒（AAV）介导的基因转移或通过使用基于Salen的EUK SOD模拟物来增加肺中SOD的表达，并在RSV感染和共暴露于ETS的实验小鼠模型中测量RSV滴度（作为主要终点）。将通过检查临床疾病、肺部炎症/病理学和病毒介导的气道高反应性来评价SOD的保护作用。该项目可能具有重要的转化意义，提出了新的和更积极的战略，以治疗原发性呼吸道病毒感染的高危婴儿（即暴露于ETS）。这些治疗机会将根据本探索性项目的结果在未来的R 01应用中进行B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.