Role of Complement Activation in Severe COVID-19

项目摘要 我们最近建立了新冠肺炎亚致死小鼠模型(K18-hACE2)。我们感染了 这些小鼠用流感病毒或亚致死性SARS-CoV-2感染K18-hACE2小鼠进行研究 目的：了解轻度Covid-19疾病的病理生物学特征，并探讨长期Covid的治疗方法。这些 研究表明，流感和亚致死剂量的SARS-CoV-2都会导致瞬时体重 肺上皮细胞的丢失和损伤与预期不谋而合。然而，流感引起的炎症是 通过组织成豆荚结构和肺的基础肺上皮细胞的增殖来解决 在亚致死性SARS-CoV-2诱导的炎症过程中再生导致肺纤维化。在 分子水平流感病毒感染诱导角蛋白基因(Krt5、15、16)在 与亚致死剂量的SARS-CoV-2相比，SARS-CoV-2的水平显著提高，与组织一致 亚致死性SARS-CoV-2感染小鼠的肺部流感修复，但肺纤维化。 重要的是，流感诱导了更强的干扰素反应，而SARS-CoV-2诱导了 更强的细胞因子反应、补体反应和纤维化。这些数据表明， 更强大的先天免疫反应，减弱的细胞因子和补体反应，以及 激活前分解分子可能有助于降低SARS冠状病毒的死亡率和发病率。 2.欧米茄3多不饱和脂肪酸(n-3 PUFA)符合这些标准，因为它们激活了 直接抗病毒反应蛋白，是促进分解的脂质介质的前体 有利于组织修复。事实上，n-3多不饱和脂肪酸可减少由各种化学和药物引起的肺纤维化 环境攻击。 在这份补充提案中，我们将用n-3病毒喂养亚致死性SARS-CoV-2感染小鼠 添加多不饱和脂肪酸或n-6多不饱和脂肪酸(对照)的日粮以检验n-3多不饱和脂肪酸将 通过缓解SARS-CoV-2感染的初始损伤来提高先天免疫应答 由体重减轻和最初的肺损伤决定。我们进一步假设，通过增加组织 而血中促分解脂类介质的浓度，n-3多不饱和脂肪酸将促进组织修复 感染亚致死剂量SARS-CoV-2的小鼠的过度纤维化。如果这些研究成功 他们将为人类临床研究开辟一条道路，旨在将n-3多不饱和脂肪酸用作营养 单独或与其他药物联合使用以减少长寒的发病率的物质 比如补体抑制剂。

PROJECT ABSTRACT We recently developed sub-lethal lethal mouse model of Covid-19 (K18-hACE2). We infected these mice with influenza virus or sublethal SARS-CoV-2 infected K18-hACE2 mice to study pathobiology of Covid-mild 19 disease and to identify treatment modalities for long Covid. These studies revealed that both influenza and sub-lethal dose of SARS-CoV-2 causes transients weight loss and damage lung epithelial cells as expected. However, influenza induced inflammation was resolved by proliferation of basal lung epithelial cells organized into pod structure and lung regeneration while sub-lethal SARS-CoV-2 induced inflammation resulted in lung fibrosis. At the molecular level influenza infection induced expression of Keratin genes (Krt5, 15, 16) at dramatically higher levels compared to sub-lethal dose of SARS-CoV-2, consistent with tissue repair in lungs of influenza but fibrosis in the lungs of sub-lethal SARS-CoV-2 infected mice. Importantly, influenza induced much stronger interferon response while SARS-CoV-2 induced much stronger cytokine response, complement response, and fibrosis. These data indicate that a more robust innate immune response, attenuated cytokine and complement response, and activation of pro-resolving molecules may help reduce the mortality and morbidity of SARS-CoV- 2. Omega 3 polyunsaturated fatty acids (n-3 PUFAs) fulfil these criteria because they activate direct anti-viral response proteins and are the precursors of the pro-resolving lipid mediators that favor tissue repair. Indeed, n-3 PUFAs reduce lung fibrosis induced by various chemical and environmental assaults. In this supplemental proposal we will feed sub-lethal SARS-CoV-2 infected mice with n-3 PUFA or n-6 PUFA (control) supplemented diets to test the hypothesis that n-3 PUFAs will improve innate immune response to SARS-CoV-2 infection by moderating the initial injury as determined by weight loss and initial lung injury. We hypothesis further that by increasing tissue and blood concentration of pro-resolving lipid mediators, n-3 PUFAs will promote tissue repair over fibrosis in mice infected with sub-lethal dose of SARS-CoV-2. If these studies are successful they will open a path for human clinical studies aimed at using n-3 PUFAs as nutritional substances to reduce morbidity of long Covid, either alone or in combination with other agents such as complement inhibitors.