Control of T Cell Recruitment to Influenza Viruses in the Lung

描述（由申请人提供）：该项目的目标是确定Th1、Th17和CD8细胞在肺部对非致病性和致病性流感病毒的转运和反应中的选择作用。这些病毒具有高度传染性，每年在世界范围内引起流行病，并伴有零星的破坏性大流行。在刚刚过去的北半球流感季节，出现了一种新的携带猪、禽和人病毒段的三重重组H1N1流感毒株。这种病毒现在正在引起世界范围的大流行。由于人们日益担心新型H1N1病毒的毒性将变得更强，并且可能发生高致病性H5N1禽流感病毒在人间传播的情况，因此制定新的战略以控制与流感病毒相关的发病率和死亡率至关重要。虽然CD4和CD8 T细胞通常通过细胞毒性和细胞因子介导的反应控制肺部流感病毒感染，但高致病性菌株可引起T细胞参与的强效和异常炎症反应。因此，了解肺中T细胞对致病性和非致病性流感病毒的反应如何不同，以确定可以靶向改善T细胞对这种感染的病理反应的机制是至关重要的。令人惊讶的是，在对流感病毒的反应中，人们对T细胞进入肺部的调节知之甚少，也不知道炎症的程度如何影响它们的功能。我们对流感小鼠模型的研究表明，Th1和Th17细胞出现在产生免疫和有限发病率的病毒剂量以及高致病性剂量的初级反应中。在免疫模型中，这些效应细胞以及应答的CD8细胞获得结合p -选择素的能力，p -选择素是一种内皮选择素，可启动向炎症部位的迁移。在缺乏功能性选择素配体或PSGL-1 (p -选择素糖蛋白配体-1)（T细胞上选择素的主要配体）的情况下，CD4 T细胞在排空LN中异常扩张，IFN-3和IL-17的产生升高，并且肺部积聚严重受损。这些数据表明，选择素-配体相互作用在调节T细胞进入肺部以及抑制效应反应方面可能具有双重作用。在这项应用中，我们提出了体内和体外研究来验证这一假设，使用缺乏PSGL-1或不能产生功能性选择素配体的小鼠、IFN-3和IL-17报告小鼠、选择素融合蛋白以及WT和工程流感病毒。这些工具将使我们能够评估CD4细胞和CD8细胞在以下特定目的中的反应：1)评估选择素在感染非致病性和致病性流感病毒后在肺部T细胞运输和定位中的作用；2)确定选择素调节效应T细胞反应的作用。我们希望通过选择素控制粘附的机制来获得对效应T细胞调节的新见解，这些选择素可以帮助保护人群免受致病性流感病毒的影响。

DESCRIPTION (provided by applicant): The goal of this project is to identify the role of selectins in the trafficking and responses of Th1, Th17, and CD8 cells to nonpathogenic and pathogenic doses of influenza viruses in the lungs. These viruses are highly contagious, and cause yearly epidemics worldwide, with sporadic, devastating pandemics. This past influenza season in the northern hemisphere saw the emergence of a new triple reassortant H1N1 influenza strain carrying swine, avian, and human segments. This virus is now causing a worldwide pandemic. Amid growing concern that the new H1N1 virus will become more virulent and the possibility human of human transmission highly pathogenic H5N1 avian virus could occur, it is crucial to develop new strategies to control the morbidity and mortality associated with influenza viruses. Although CD4 and CD8 T cells typically control influenza virus infection in the lungs via cytotoxic- and cytokine-mediated responses, highly pathogenic strains can cause potent and aberrant inflammatory responses to which T cells contribute. It is therefore critical to understand how T cell responses to pathogenic vs nonpathogenic influenza viruses differ in the lungs to identify mechanisms that could be targeted to ameliorate pathological responses of T cells to this infection. Surprisingly little is known about the regulation of T cell trafficking into the lungs in the response to influenza viruses or how the magnitude of inflammation could affect their function. Our studies of the murine model of influenza have shown that Th1 and Th17 cells arise in the primary response with doses of virus that produce immunity and limited morbidity as well as with doses that are highly pathogenic. In the model of immunity, these effector cells, as well as responding CD8 cells, acquire the capacity to bind P-selectin, an endothelial selectin which initiates migration into sites of inflammation. In the absence of functional selectin ligands or PSGL-1 (P-selectin glycoprotein ligand-1), a major ligand for selectins on T cells, CD4 T cells have aberrant expansion and elevated production of IFN-3 and IL-17 in the draining LN, as well as greatly impaired accumulation in the lungs. The data suggest the hypothesis that selectin-ligand interactions could have a dual role in regulating T cell trafficking into the lungs as well as in dampening the effector response. In this application, we propose in vivo and in vitro studies to test this hypothesis using mice that are deficient in PSGL-1, or are unable generate functional selectin ligands, IFN-3 and IL-17 reporter mice, selectin fusion proteins, and WT and engineered influenza viruses. These tools will enable us to assess the responses CD4 cells and CD8 cells in the following specific aims: 1) to evaluate the role of selectins in T cell trafficking and localization in the lungs after infection with non-pathogenic and pathogenic doses of influenza virus; and 2) to determine the role of selectins regulating the responses of effector T cells. We hope to gain new insights into the regulation of effector T cells through mechanisms that control adhesion via selectins that could be targeted to help protect the population from the consequences of pathogenic influenza viruses. PUBLIC HEALTH RELEVANCE: If we find previously unidentified roles for selectins T cell recruitment or responses in the lungs after influenza infection, we will have identified a new mechanism of T cell regulation in the pulmonary response to this virus. If targeting of cells via selectins can reduce inflammation, synthetic selectin inhibitors that are already in use in murine models of disease might offer a new clinical approach to control pathogenic responses to influenza viruses.