Balancing epithelial cell resistance and resilience to respiratory viral infections

项目总结 新冠肺炎大流行突显了一种呼吸道核糖核酸病毒如何能够诱导 主办方结果。虽然我们在了解临床、细胞和分子方面的相关性方面取得了进展 疾病的严重性，很少有研究评估基线上存在的特定因素是否或如何导致严重的 疾病。在疾病严重程度的相关性是否代表因果因素方面存在巨大的知识差距。 (即，如果存在基线会导致更严重的感染)，或者实际上可能代表一般有益的尝试 在恢复仅在选定宿主环境中有害的组织功能(即，弹性机制)方面。尽管 SARS-CoV-2与流感具有不同的生物学特征，流行病学研究已经注意到超重和肥胖 个体患严重感染的风险更大，这牵涉到脂质代谢，而且进一步的遗传学研究已经 在严重病例中发现了I/III型干扰素系统的突变。重要的是，治疗根本原因 严重的病毒性呼吸道疾病的发生需要更深入地了解导致呼吸道疾病的上皮细胞状态 不同的结果，以设计宿主指导的疗法，以补充疫苗接种活动，并避免长期- 对呼吸系统和心血管系统造成持久损害。 最近，通过对鼻咽拭子进行单细胞RNA测序(scRNA-seq)，我们发现 干扰素抗病毒反应减弱，细胞内胆固醇生物合成潜力增加 在呼吸道上皮细胞中，重度与轻中度新冠肺炎的特点是。在同一项研究中，我们还 显示分泌细胞和杯状细胞的不同亚群，具有未知的功能潜力，重叠 与我们之前在季节性流感研究中确定的亚群。我们公布的数据，连同 要求进一步研究先前存在的抗病毒和胆固醇生物合成细胞是如何 人类呼吸道上皮细胞的状态决定了宿主对呼吸道病毒感染的结果。 根据这些发现，我们假设呼吸道上皮细胞的基线胆固醇生物合成是 一种关键的宿主弹性机制，在缺乏有效的抗病毒抗性的情况下变得致病 机械装置。这个最重要的假设只能通过概念和实验的转变来检验 我们传统上采用的方法(新研究方向)。成功测试我们的假设将解决 (目的1)胆固醇生物合成是否决定了呼吸道上皮细胞的最大潜在干扰素反应 或者干扰素反应减弱是否是小鼠胆固醇生物合成增强的基础。此外， 它将确定呼吸道上皮细胞对局部和有机体脂肪代谢的新贡献。我们的工作将 也测试(目标2)人类上皮祖细胞代谢和抗病毒细胞表型的稳定性。 我们的计划的成功完成将导致开发非侵入性筛查方法，以更好地 确定易感人群感染呼吸道病毒的风险，以及预防和治疗策略 在呼吸道内实现宿主防御策略的最佳平衡。

PROJECT SUMMARY The COVID-19 pandemic has highlighted how one respiratory RNA virus can induce a tremendous diversity of host outcomes. While we have made progress in understanding clinical, cellular, and molecular correlates of disease severity, few studies have assessed if or how specific factors present at baseline may induce severe disease. There is a tremendous knowledge gap in whether correlates of disease severity represent causal factors (i.e. if presence at baseline lead to more severe infection), or may actually represent generally beneficial attempts at restoring tissue function (i.e. a resilience mechanism), that are detrimental only in select host contexts. Despite distinct biology of SARS-CoV-2 and influenza, epidemiological studies have noted that overweight and obese individuals are at greater risk for severe infection, implicating lipid metabolism, and further genetic studies have found mutations in the Type I/III interferon system in severe cases. Importantly, treating the underlying causes of severe viral respiratory diseases will require a deeper understanding of the epithelial cell states that contribute to diverse outcomes to design host-directed therapies that complement vaccination campaigns and avoid long- lasting damage to the respiratory and cardiovascular systems. Recently through single-cell RNA-sequencing (scRNA-seq) of nasopharyngeal swabs, we have discovered that a muted interferon antiviral response combined with an increase in intracellular cholesterol biosynthesis potential in respiratory epithelial cells characterizes severe vs. mild-moderate COVID-19. In this same study, we also revealed diversified subsets of secretory and goblet cells with uncharacterized functional potential, overlapping with subsets we had previously identified in a study of seasonal influenza. Our published data, together with that of our colleagues, mandate further investigation into how pre-existing antiviral and cholesterol biosynthetic cell states in human respiratory epithelial cells dictate host outcomes to respiratory viral infection. In light of these findings, we hypothesize that baseline cholesterol biosynthesis in respiratory epithelial cells is a critical host resilience mechanism which becomes pathogenic in the absence of effective antiviral resistance mechanisms. This overarching hypothesis can only be tested through a shift in the conceptual and experimental approaches we traditionally deploy (New Research Direction). Successfully testing our hypothesis will address (Aim 1) whether cholesterol biosynthesis dictates the maximum potential interferon response in airway epithelial cells, or whether a muted interferon response underlies enhanced cholesterol biosynthesis in mice. Furthermore, it will identify novel contributions of airway epithelial cells to local and organismal lipid metabolism. Our work will also test (Aim 2) the stability of metabolic and antiviral cellular phenotypes in human epithelial progenitor cells. Successful completion of our plan will lead to the development of non-invasive screening approaches to better ascertain risk of susceptible populations to respiratory viruses, and of prophylactic and therapeutic strategies to achieve optimal balance of host defense strategies in the respiratory tract.