Control of T Cell Recruitment to Influenza Viruses in the Lung

描述(由申请人提供)：本项目的目标是确定选择素在Th1、Th17和CD8细胞对肺部非致病性和致病性剂量的流感病毒的运输和反应中的作用。这些病毒具有很高的传染性，每年在全球范围内引起流行病，并伴随着零星的破坏性大流行。在过去的北半球流感季节，出现了一种新的三重组合H1N1流感病毒株，携带猪、禽和人的片段。这种病毒现在正在引起一场全球大流行。随着人们越来越担心新的H1N1病毒将变得更加毒力，以及可能发生人类传播高致病性H5N1禽流感病毒的可能性，制定新的战略来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CD8T细胞通常通过细胞毒性和细胞因子介导的反应控制流感病毒在肺部的感染，但高致病性菌株可以引起强大的和异常的炎症反应，T细胞参与其中。因此，了解T细胞对致病性和非致病性流感病毒的反应在肺部有何不同，以确定可能针对改善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，人们对T细胞在应对流感病毒时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。我们对小鼠流感模型的研究表明，Th1和Th17细胞出现在产生免疫力和有限发病率的病毒剂量以及高致病性剂量的主要反应中。在免疫模型中，这些效应细胞以及反应的CD8细胞获得了结合P-选择素的能力，P-选择素是一种内皮选择素，可以启动向炎症部位的迁移。在缺乏功能性选择素配体或T细胞上选择素的主要配体PSGL-1(P-选择素糖蛋白配体-1)的情况下，CD4T细胞在引流的LN中异常扩张，产生更多的干扰素-3和IL-17，并严重损害肺内的蓄积。这些数据提出了这样的假设，即选择素-配体的相互作用可能在调节T细胞进入肺部以及抑制效应器反应方面具有双重作用。在这一应用中，我们建议在体内和体外进行研究，使用PSGL-1缺陷或不能产生功能性选择素配体的小鼠、干扰素-3和IL-17报告小鼠、选择素融合蛋白以及WT和工程流感病毒来验证这一假设。这些工具将使我们能够评估CD4细胞和CD8细胞在以下特定目标中的反应：1)评估选择素在非致病剂量和致病剂量流感病毒感染后T细胞在肺内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。我们希望通过通过选择素来控制黏附的机制来获得对效应器T细胞调控的新见解，这种机制可能是靶向的，以帮助保护人群免受致病性流感病毒的影响。 公共卫生相关性：如果我们在流感感染后发现选择素T细胞募集或反应在肺中扮演以前未知的角色，我们将确定T细胞调节肺对这种病毒反应的新机制。如果通过选择素靶向细胞可以减少炎症，那么已经在小鼠疾病模型中使用的合成选择素抑制剂可能会提供一种新的临床方法来控制对流感病毒的致病反应。

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.