Determining age dependent factors driving COVID-19 disease severity using experimental human paediatric and adult models of SARS-CoV-2 infection

严重急性呼吸综合征冠状病毒2型(SARS-CoV-2)引起了新冠肺炎的全球大流行。我们对SARS-CoV-2在人类呼吸道的发病机制缺乏了解，这是制定有效的新冠肺炎治疗策略的重要障碍。到目前为止，我们知道新冠肺炎疾病的严重程度随着年龄的增长而增加，儿童中很少有严重病例。中国的病死率为60岁，上升到15%。该项目将侧重于宿主对感染反应的两个方面，研究呼吸道内的细胞如何对病毒作出反应，以及招募的免疫细胞(重点关注最先对感染作出反应的中性粒细胞的行为)是否有助于减少病毒载量或导致呼吸道损伤和呼吸道碎片堆积。我们将使用一个实验性的SARS-CoV-2呼吸道上皮感染模型，该模型来自幼儿、成人和老年人。我们的目标是确定：1)老年人的主要感染部位-鼻黏膜上皮-是否表现出比儿童更多的病毒复制和对SARS-CoV-2感染的炎症反应增强。2)通过对培养细胞进行单细胞基因组分析，并将结果与年龄匹配的新冠肺炎患者的相同数据进行比较，确定支配年龄决定因素的分子机制。3)通过测量a)免疫细胞的强度(通过测量a)免疫细胞(A)免疫细胞的强度(重要的是，我们要了解这些基本反应差异的原因，以便帮助确定这些年龄段的新冠肺炎病最合适的治疗方法是什么。关于新的和现有的抗病毒药物以及免疫调节剂疗法的效用，包括非类固醇抗炎药和托西珠单抗，存在很大争议。该项目将迅速提供关于病毒发病机制和这些与年龄相关的当事人在疾病结果中的原因的新理解。这不仅将有助于在短期内支持有效治疗药物的开发，强调这一模式与抗病毒候选药物临床前评估的相关性，而且还可能突出可用于开发长期早期干预或预防治疗的重要风险因素或保护机制。

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused a worldwide pandemic of COVID-19. Our lack of understanding about the pathogenesis of SARS-CoV-2 in the human airways is an important barrier to developing effective treatment strategies for COVID-19. So far, we know that COVID-19 disease severity increases with age, with very few severe cases among children. In China, the case fatality ratio was 60-year olds, rising to 15% in those >80. This project will focus on two aspects of the host response of infection, studying how the cells that line the airway respond to the virus, and whether the recruited immune cells (focussing on the behaviour of neutrophils that are the first to respond to infection) the help reduce viral load or contribute to airway damage and the build-up of debris in the airways. We will use an experimental SARS-CoV-2 infection model of the airway epithelium from young children, adults and the elderly. Our objectives are to determine: 1) if the primary site of infection - the nasal epithelium - of the elderly exhibit increased viral replication and increased inflammatory response to SARS-CoV-2 infection compared to children.2) the molecular mechanisms that govern age-determinants of COVID-19 disease severity using single-cell genomic analysis of cultured cells and comparing outputs to the same data from age-matched COVID-19 patients using scRNAseq.3) whether the innate immune response to SARS-CoV2 infected airway epithelium exacerbates inflammation and contributes to the severity of illness in the elderly by measuring a) the intensity of immune cell (neutrophil) recruitment to the airway b) epithelial damage and c) neutrophil phenotype and function.It is important that we understand the reasons for these fundamental differences in responses in order to help determine what the most appropriate therapy is for COVID-19 disease in these age groups. There is much debate about the utility of novel and exsiting anti-virals as well as immune modulator therapies including NSAIDs and Tocilizumab. This project will rapidly deliver new understanding about the viral pathogenesis and the cause of these age-related disparties in disease outcomes. Not only will this help support the development of effective therapeutics in the short-term, underlining the relevance of this model for the preclinical evaluation of antiviral candidates, but it may also highlight important risk factors or protective mechanisms that could be used to develop early interventional or prophylaxtic therapies in the long-term.