Defining the role of natural killer cells in COVID-19

项目总结 严重的新冠肺炎会导致外周免疫系统的强烈变化。某些免疫细胞类型需要 关于这种疾病的保护作用，而其他人则对疾病病理做出贡献。一种细胞类型，其 新冠肺炎中的功能作用尚不清楚的是自然杀伤(NK)细胞。我之前演示过NK 严重的新冠肺炎会强烈改变能够调节抗病毒活动的细胞。我还产生了 SARS-CoV-2调控NK细胞活化配体表达的初步研究 受体NKG2D并允许感染细胞避免NK细胞的杀伤；然而，其背后的机制 仍未被开发。此外，尽管新冠肺炎患者的NK细胞是很差的细胞毒介质 新冠肺炎患者NK细胞对肿瘤靶细胞的功能应答 尚未对感染SARS-CoV-2的细胞进行检查。拟议的研究试图解决这些关键问题 通过对SARS-CoV-2免疫应答机制的研究，我们对SARS-CoV-2免疫应答的认识存在差距 新冠肺炎中NK细胞的表型和功能。要做到这一点，我将1)定义 SARS-CoV-2对NK细胞应答的调节作用 具有广泛疾病严重性的新冠肺炎患者对感染SARS-CoV-2的目标细胞的抵抗力；以及 3)阐明单核细胞-NK细胞串扰在重症新冠肺炎患者NK细胞衰竭中的作用。我 假设我的提案中描述的实验将显示外周的长时间刺激 单核细胞的NK细胞导致重症新冠肺炎患者NK细胞的耗竭，从而导致贫困 免疫逃避加剧对SARS-CoV-2感染靶细胞的功能反应 SARS-CoV-2介导的机制。为了验证这一假设，我将使用来自 疾病严重程度从轻微症状到致命不等的大量新冠肺炎患者。这就做 进行功能分析，测试这些NK细胞对感染的靶细胞的反应 斯坦福大学BSL3设施中具有复制能力的SARS-CoV-2。我还将评估单核细胞从 新冠肺炎危重患者共培养诱导健康NK细胞活化和耗竭 具有这两种细胞类型的系统。总体而言，我的实验将揭示NK细胞表型的基础 在新冠肺炎观察到，这种表型对NK细胞对SARS-CoV-2感染细胞应答的影响，以及 SARS-CoV-2调节感染细胞对NK细胞杀伤敏感性的机制。 彻底询问NK细胞对SARS-CoV-2的反应将有助于确定 新冠肺炎中的NK细胞是保护性的或病理性的，将促进我们对NK细胞的集体理解 生物学。此外，识别参与调节NK细胞激活的受体将使 新冠肺炎治疗策略的发展。

PROJECT SUMMARY Severe COVID-19 induces strong alterations in the peripheral immune system. Some immune cell types take on a protective role in this disease, while others contribute to disease pathology. One cell type whose functional role in COVID-19 is not yet known is the natural killer (NK) cell. I previously demonstrated that NK cells, which can mediate antiviral activity, are strongly altered by severe COVID-19. I have also generated preliminary data demonstrating that SARS-CoV-2 modulates the expression of ligands for the NK cell activating receptor NKG2D and allows infected cells to avoid NK cell killing; however, the mechanisms underlying this remain unexplored. Moreover, although the NK cells of COVID-19 patients are poor mediators of cytotoxicity against tumor target cells, the functional responses of NK cells from COVID-19 patients to SARS-CoV-2-infected cells have not been examined. The proposed research seeks to resolve these critical gaps in our knowledge of the immune response to SARS-CoV-2 by investigating the mechanisms underlying the phenotype and function of NK cells in COVID-19. To do this, I will 1) Define the mechanisms by which SARS-CoV-2 modulates NK cell responses; 2) Characterize the functional responses of NK cells from COVID-19 patients with a wide range of disease severities against target cells infected with SARS-CoV-2; and 3) Elucidate the role of monocyte-NK cell crosstalk in driving NK cell exhaustion in severe COVID-19. I hypothesize that the experiments described in my proposal will show that prolonged stimulation of peripheral NK cells by monocytes contributes to exhaustion in the NK cells of severe COVID-19 patients, driving poor functional responses against SARS-CoV-2-infected target cells that are exacerbated by immune evasion mechanisms mediated by SARS-CoV-2. To test this hypothesis, I will utilize NK cells and monocytes from a large cohort of COVID-19 patients with disease severities ranging from mildly symptomatic to fatal. I will perform functional assays that test the responses of these NK cells against target cells infected with replication-competent SARS-CoV-2 in Stanford’s BSL3 facilities. I will also assess the ability of monocytes from severe COVID-19 patients to induce activation and exhaustion in healthy NK cells by establishing a co-culture system with these two cell types. Overall, my experiments will uncover the basis for the NK cell phenotype observed in COVID-19, the effects of this phenotype on NK cell responses to SARS-CoV-2-infected cells, and the mechanisms by which SARS-CoV-2 modulates the susceptibility of infected cells to NK cell cytotoxicity. Thoroughly interrogating the responses of NK cells to SARS-CoV-2 will help to determine whether the role of NK cells in COVID-19 is protective or pathological and will further our collective understanding of NK cell biology. Moreover, the identification of receptors involved in the modulation of NK cell activation will inform the development of therapeutic strategies for COVID-19.