Regulation of the host immune response to influenza by the checkpoint receptor Tim3

项目摘要 流感仍然是发病率和死亡率的重要原因，目前的治疗方法疗效有限。 流感中的呼吸衰竭是由病毒复制延长或由流感病毒引起的肺损伤引起的。 过度的免疫反应因此，更好地了解调节机制， 宿主对IAV的免疫反应可能导致新的治疗方法。效应CD 8 + T细胞负责 甲型流感病毒（IAV）在原发感染期间的清除，但也涉及免疫- 介导的肺损伤。效应CD 8 + T细胞也引起流感特异性CD 8+组织驻留记忆 T细胞（Trm），介导异亚型免疫，降低随后的IAV感染的严重程度。 因此，必须严格控制CD 8 + T细胞对IAV应答的幅度和质量，以实现 病毒清除，限制免疫介导的肺损伤，促进组织驻留记忆的形成。 树突状细胞（DC）激活淋巴结中的幼稚T细胞以产生效应CD 8 + T细胞应答， 与感染肺内效应CD 8 + T细胞相互作用以促进病毒清除并减弱 免疫病理学和所需的最佳的CD 8 + Trm的产生。因此，DC在以下方面发挥着关键作用： 调节效应CD 8 + T细胞和保护性记忆的形成。效应CD 8 + T细胞是 也由抑制性（即检查点）受体调节。T细胞免疫球蛋白和粘蛋白结构域3（Tim 3） 是一种重要的检查点受体，在活化的T细胞上诱导并在 DC. Tim 3调节对IAV的免疫应答，但不知道它是否限制病毒清除 或保护肺免受损伤。我们先前证明Tim 3减弱效应CD 8 + T细胞应答 并在IAV小鼠模型中防止死亡。我们现在有数据表明Tim 3 促进DC的抗原交叉呈递-这是产生效应子和组织的关键过程 常驻记忆CD 8 + T细胞在IAV感染中的作用我们的中心假设是Tim 3决定了 病毒清除和肺损伤之间的平衡，并促进CD 8 + Trm的形成。在目标#1中，我们 将检验Tim 3通过DC和DC介导的活化促进抗原交叉呈递的假设 在IAV感染期间，初始CD 8 + T细胞的数量。具体而言，我们将（A）确定细胞内机制 （B）表征Tim 3在细胞上的表达和功能， 人肺DC，和（C）确定肺DC上的Tim 3在IAV过程中活化幼稚CD 8 + T细胞中的作用 感染在目标#2中，我们将测试Tim 3促进病毒清除并减弱免疫抑制的假设。 在IAV感染期间介导肺损伤，并促进IAV诱导的CD 8 + Trm形成。实验 该目的将：A）确定IAV期间Tim 3在调节肺中效应CD 8 + T细胞应答中的作用， 感染和（B）确定Tim 3在IAV诱导的CD 8 + Trm形成中的作用。这些实验 这是开发Tim 3作为流感治疗靶点的关键第一步。

PROJECT SUMMARY Influenza remains an important cause of morbidity and mortality and current therapies have limited efficacy. Respiratory failure in influenza results from either prolonged viral replication or lung injury induced by an over exuberant immune response. It follows that a better understanding of the mechanisms that regulate the host immune response to IAV could lead to new therapies. Effector CD8+ T cells are responsible for clearance of influenza A virus (IAV) during primary infection but have also been implicated in immune- mediated lung injury. Effector CD8+ T cells also give rise to influenza-specific CD8+ tissue resident memory T cells (Trm), which mediate heterosubtypic immunity, decreasing the severity of subsequent IAV infection. Thus, the magnitude and quality of the CD8+ T cell response to IAV must be tightly controlled to achieve viral clearance, limit immune-mediated lung injury and promote the formation of tissue-resident memory. Dendritic cells (DC) activate naïve T cells in the lymph node to generate an effector CD8+ T cell response, interact with effector CD8+ T cells within infected lung to promote viral clearance and attenuate immunopathology and are required for the generation of optimal CD8+ Trm. Thus, DC play a critical role in regulating both effector CD8+ T cells and in the formation of protective memory. Effector CD8+ T cells are also regulated by inhibitory (i.e. checkpoint) receptors. T cell immunoglobulin and mucin domain 3 (Tim3) is an important checkpoint receptor that is induced on activated T cells and constitutively expressed on DC. Tim3 modulates the immune response to IAV, but it is not known whether it constrains viral clearance or protects from lung injury. We previously demonstrated Tim3 attenuates effector CD8+ T cell responses and protects against mortality in a mouse model of IAV. We now have data demonstrating that Tim3 promotes antigen cross presentation by DC – a process critical for generating both effector and tissue resident memory CD8+ T cells in IAV infection. Our central hypothesis is that Tim3 determines the balance between viral clearance and lung injury and promotes the formation of CD8+ Trm. In Aim #1, we will test the hypothesis that Tim3 promotes antigen cross presentation by DC and DC-mediated activation of naive CD8+ T cells during IAV infection. Specifically, we will (A) identify the intracellular mechanisms utilized by Tim3 to promote cross presentation, (B) characterize the expression and function of Tim3 on human lung DC, and (C) determine the role of Tim3 on lung DC in activating naïve CD8+ T cells during IAV infection. In Aim #2, we will test the hypothesis that Tim3 promotes viral clearance and attenuates immune- mediated lung injury during IAV infection and promotes IAV-induced CD8+ Trm formation. Experiments in this aim will A) define the effect of Tim3 in regulating effector CD8+ T cell responses in the lung during IAV infection and (B) determine the role of Tim3 in IAV-induced CD8+ Trm formation. These experiments are a critical first step toward developing Tim3 as a therapeutic target for influenza.