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

项目总结/摘要 严重急性呼吸综合征冠状病毒2（SARS-CoV 2）感染可导致冠状病毒病 2019年（COVID-19），其特征是肺部和其他器官的急性炎症，如 心脏和肠道越来越清楚的是，SARS-CoV 2的发病机制涉及抑制 抗病毒先天免疫和诱导炎症反应。SARS-CoV 2抑制了 抗病毒I型干扰素（IFN），从而逃避早期抗病毒免疫的破坏。 随后诱导的炎症反应推动了COVID-19的发展。了解如何 SARS-CoV 2抑制I型IFN表达并诱导炎症反应，这对于设计 治疗方法。基于对SARS-CoV（SARS-CoV 2的同源物）的研究， 蛋白质与宿主免疫系统的相互作用有关，有助于抑制 I IFN应答和促炎细胞因子的诱导。本补充申请的主要目的是 是了解SARS-CoV 2蛋白抑制抗病毒先天免疫的机制， 刺激加剧的炎症反应。我们将实现两个具体目标。 在具体目标1中，我们将研究SARS-CoV 2蛋白如何抑制TBK 1信号传导和抗病毒先天性 免疫力正如在母授权中所描述的，TBK 1是一种激酶，它响应来自Toll样细胞的信号， 受体（TLR）和其他模式识别受体（PRR）在病毒感染和介导诱导 I型干扰素。与此同时，TBK 1负调节促炎细胞因子诱导， 加剧了炎症。我们的父母资助重点是阐明TBK 1如何调节TLR信号传导 和肠道微生物引起的肠道炎症。在本补充申请中，我们将具体 解决SARS-CoV 2蛋白如何调节TBK 1信号转导抑制抗病毒免疫， 刺激炎症。我们将检验我们的假设，即SARS对TBK 1信号的抑制- CoV 2蛋白不仅抑制I型IFN的产生，而且还促进炎症反应。 在具体目标2中，我们将系统地定义SARS-COV 2蛋白诱导 使用细胞培养物和小鼠模型的炎症反应。我们将研究信号通路 参与SARS-CoV 2诱导的巨噬细胞和上皮细胞中促炎细胞因子的表达。 我们还将研究SARS-CoV 2的刺突蛋白如何下调其细胞受体血管紧张素- 转化酶2（ACE 2）。由于ACE 2是一种关键的抗炎因子，我们假设Spike 蛋白质诱导的ACE 2下调对肺和肠炎症的诱导起关键作用。 我们认为，这些研究提出了新的机制，介导的发病机制， COVID 19并将对COVID 19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.