Molecular mechanisms underlying immunosuppression and inflammation caused by SARS-CoV2 proteins

项目摘要/摘要 感染严重急性呼吸综合征冠状病毒2型导致冠状病毒病 2019年(新冠肺炎)，以肺部和其他器官的急性炎症为特征，如 心脏和肠道。越来越清楚的是，SARS-CoV2的发病机制涉及抑制 抗病毒先天免疫和诱导炎症反应。SARS-CoV2抑制小鼠肝细胞病变的诱导 抗病毒I型干扰素(IFN)，从而通过早期的抗病毒免疫逃脱破坏。 随后诱导的炎症反应推动了新冠肺炎的发展。了解如何 SARS-CoV2抑制I型干扰素表达并诱导炎症反应，对设计至关重要 治疗方法。根据对SARS-CoV的研究，SARS-CoV与SARS-CoV2有密切的同源物，几种病毒 蛋白质参与了与宿主免疫系统的相互作用，有助于抑制类型 干扰素应答和促炎细胞因子的诱导。这项补充申请的主要目标是 是为了了解SARS-CoV2蛋白抑制抗病毒先天免疫和 刺激加剧了炎症反应。我们将实现两个具体目标。 在特定的目标1中，我们将研究SARS-CoV2蛋白是如何抑制TBK1信号和抗病毒的 豁免权。正如在父母拨款中所描述的那样，TBK1是一种对来自Toll-like的信号做出反应的激酶 病毒感染中的受体(TLR)和其他模式识别受体(PRRs)及其介导的诱导 I型IFN。同时，TBK1负性调节促炎细胞因子的诱导，从而防止 加剧了炎症。我们的父母资助重点是阐明TBK1如何调节TLR信号 以及肠道微生物引起的肠道炎症。在这份补充申请中，我们将具体说明 阐述SARS-CoV2蛋白在抑制抗病毒免疫中如何调节TBK1信号和 刺激炎症。我们将检验我们的假设，即SARS抑制TBK1信号- CoV2蛋白不仅能抑制I型干扰素的产生，还能促进炎症反应。 在具体目标2中，我们将系统地定义SARS-COV2蛋白诱导 使用细胞培养和小鼠模型的炎症反应。我们将研究信号通路。 参与SARS-CoV2诱导巨噬细胞和上皮细胞表达促炎细胞因子。 我们还将研究SARS-CoV2的刺突蛋白如何下调其细胞受体血管紧张素-2。 转化酶2(ACE2)。由于ACE2是一种关键的抗炎因子，我们假设Spike 蛋白诱导的血管紧张素转换酶2下调在肺和肠道炎症的诱导中起重要作用。 我们认为，这些拟议的研究解决了新的机制，介导了 COVID19，并将对COVID19疗法产生重要影响。

PROJECT SUMMARY/ABSTRACT Infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) causes coronavirus disease 2019 (COVID-19), which is characterized by acute inflammation in the lung and other organs, such as the heart and intestine. It is increasingly clear that the pathogenesis of SARS-CoV2 involves suppression of antiviral innate immunity and induction of inflammatory responses. SARS-CoV2 suppresses induction of the antiviral type I interferons (IFNs) and, thereby, escapes from destruction by the early phase antiviral immunity. Subsequent induction of inflammatory responses drives the development of COVID-19. Understanding how SARS-CoV2 suppresses type I IFN expression and induces inflammatory responses, is crucial for designing therapeutic approaches. Based on the studies of SARS-CoV, the close homolog of SARS-CoV2, several viral proteins have been implicated in the interplay with host immune system, contributing to the suppression of type I IFN responses and induction of proinflammatory cytokines. The major goal of this supplementary application is to understand the mechanisms by which SARS-CoV2 proteins suppress antiviral innate immunity and stimulate exacerbated inflammatory responses. We will perform two specific aims. In Specific Aim 1, we will examine how SARS-CoV2 proteins suppress TBK1 signaling and antiviral innate immunity. As described in the parent grant, TBK1 is a kinase that responds to signals from the toll-like receptors (TLRs) and other pattern-recognition receptors (PRRs) during viral infections and mediates induction type I IFNs. At the same time, TBK1 negatively regulates proinflammatory cytokine induction to prevent exacerbated inflammation. Our parental grant focuses on the elucidation of how TBK1 regulates TLR signaling and intestinal inflammation caused by gut microbes. In this supplementary application, we will specifically address how SARS-CoV2 proteins modulate TBK1 signaling in the suppression of antiviral immunity and stimulation of inflammation. We will examine our hypothesis that suppression of TBK1 signaling by SARS- CoV2 proteins not only inhibits type I IFN production but also promotes inflammatory responses. In Specific Aim 2, we will systematically define the mechanisms by which SARS-COV2 proteins induce inflammatory responses using both cell culture and mouse models. We will examine the signaling pathways involved in SARS-CoV2-induced expression of proinflammatory cytokines in macrophages and epithelial cells. We will also examine how the Spike protein of SARS-CoV2 downregulates its cellular receptor, angiotensin- converting enzyme 2 (ACE2). Since ACE2 is a pivotal anti-inflammatory factor, we hypothesize that Spike protein-induced ACE2 downregulation critically contributes to the induction of lung and intestinal inflammation. We believe that these proposed studies address novel mechanisms that mediate the pathogenesis of COVID19 and will have important implications for COVID19 therapies.