The effect of type I IFN and IL-12 signaling on T cell immunity to tuberculosis

描述（由申请人提供）：结核分枝杆菌（Mtb）是本提案的重点，是一种成功的人类病原体，通过多种机制破坏和逃避宿主免疫。在对感染的应答中，先天免疫系统的细胞产生IL-12和I型干扰素（IFN）。干扰素是一个具有多种活性的细胞因子家族 调节免疫力和介导对病原体的保护。虽然IL-12对于人和啮齿动物的抗分枝杆菌免疫是必需的，但I型IFN对宿主抗结核的免疫是有害的。重要的是，已经定义了一种“结核病特征”，将活动性结核病患者与潜伏性感染者区分开来。该签名由嗜中性粒细胞驱动的IFN诱导型基因谱主导。免疫系统的几个组成部分对结核分枝杆菌的抵抗力有不利影响。为什么I型干扰素会对结核分枝杆菌的免疫力产生不利影响尚不清楚，这也是本提案的重点。I型IFN在急性病毒感染期间调节NK和CD 8 + T细胞的活化、扩增和效应子功能。我们推测I型IFN对Mtb免疫的不利影响是通过对T细胞应答的抑制作用介导的。战略iNKT细胞位于先天免疫和适应性免疫之间的交叉点，与NK细胞和常规T细胞具有共同特征。我们的数据表明，干扰素？显着抑制IL-12和TCR驱动的IFN？iNKT细胞的生产。iNKT细胞具有识别Mtb感染的巨噬细胞并限制细菌生长的先天能力。它们的体外抗菌活性表明它们在体内应该是有益的。然而，iNKT细胞对于Mtb免疫来说是不可或缺的，可能是因为它们在体内变得无反应性。相反，它们的特异性激活会影响Mtb感染后的存活率。在目的1中，我们将使用来自I型IFN受体（IFNAR）敲除或WT小鼠的巨噬细胞和iNKT细胞来确定由Mtb感染的细胞产生的I型IFN如何影响iNKT细胞功能。在目标2中，我们将确定I型IFN如何影响体内对Mtb的T细胞免疫。将使用混合骨髓（BM）嵌合小鼠，使得暴露于相同细菌负荷和炎性环境的IFNAR-/-和WT T细胞可以平行研究。使用这些混合的BM嵌合小鼠，我们将确定T细胞的I型IFN信号传导如何影响它们在Mtb感染期间的扩增、存活和获得效应子功能。一组不同的混合嵌合小鼠将用于确定T细胞的I型IFN信号传导是否影响宿主对Mtb感染的抗性。将使用90% TCR？-/-制备嵌合小鼠BM和10%WT或IFNAR-/- BM。这些小鼠中几乎所有的B细胞、巨噬细胞和DC将表达IFNAR;而所有的T细胞将分别是WT或IFNAR-/-。通过用Mtb攻击这些嵌合小鼠，我们可以确定T细胞的I型IFN信号传导是否是宿主抗性所需的。摘要我们的体外和体内模型将确定I型IFN如何影响T细胞对Mtb的免疫。我们期望这些实验将解释为什么I型IFN在慢性结核病期间对宿主有害，并可能表明如何操纵I型IFN信号以治疗结核病，特别是耐药病例。 公共卫生相关性：肺结核是由结核分枝杆菌引起的疾病，对全球健康构成威胁。感染通常是无症状的，因为免疫系统能够限制细菌生长。当免疫系统不再能够控制感染时，结核病就会发生。这项研究计划旨在确定为什么I型干扰素，一种在对许多病原体的免疫过程中至关重要的细胞因子，对宿主对M。结核我们假设I型干扰素损害T细胞介导的免疫。我们希望通过了解免疫反应的哪些特征是有害的，以及哪些是有益的，我们可以更好地制定干预措施，包括疫苗接种和免疫调节，这将有助于预防或治疗结核病。

DESCRIPTION (provided by applicant): Mycobacterium tuberculosis (Mtb), the focus of this proposal, is a successful human pathogen that subverts and evades host immunity by multiple mechanisms. In response to infection, cells of the innate immune system produce IL-12 and type I interferons (IFN). Interferons are a family of diverse cytokines that have myriad activities in regulating immunity and mediating protection against pathogens. While IL-12 is essential for anti-mycobacterial immunity in both people and rodents, type I IFN is detrimental to host immunity against tuberculosis. Importantly, a "TB signature" has been defined that distinguishes active TB patients from those latently infected. The signature is dominated by a neutrophil-driven IFN-inducible gene profile. Few components of the immune system adversely affect resistance to Mtb. Why type I IFN should adversely affect immunity to Mtb is unknown and is the focus of this proposal. Type I IFN regulates the activation, expansion, and effector function of NK and CD8+ T cells during acute viral infection. We hypothesize that the detrimental effect of type I IFN on immunity to Mtb is mediated by an inhibitory effect on the T cell response. Strategy. iNKT cells sit at the intersection between the innate and adaptive immunity and share features with both NK cells and conventional T cells. Our data shows that IFN? dramatically inhibits IL-12 and TCR-driven IFN? production by iNKT cells. iNKT cells have an innate capacity to recognize Mtb infected macrophages and restrict bacterial growth. Their antibacterial activity in vitro suggests that they should be beneficial in vivo. However, iNKT cells are dispensable for immunity to Mtb, possibly because they become anergic in vivo. In contrast, their specific activation prolongs survival after Mtb infection. In Aim 1, we will use macrophages and iNKT cells derived from type I IFN receptor (IFNAR) knockout or WT mice to determine how type I IFN produced by Mtb infected cells affects iNKT cell function. In Aim 2, we will determine how type I IFN affects T cell immunity to Mtb in vivo. Mixed bone marrow (BM) chimeric mice will be used so that IFNAR-/- and WT T cells, exposed to the same bacterial load and inflammatory milieu, can be studied in parallel. Using these mixed BM chimeric mice, we will determine how type I IFN signaling by T cells affects their expansion, survival and acquisition of effector function during Mtb infection. A different set of mixed chimeric mice will be used to determine whether type I IFN signaling by T cells affects host resistance to Mtb infection. Chimeric mice will be made using 90% TCR?-/- BM and 10% WT or IFNAR-/- BM. Nearly all B cells, macrophages and DC in these mice will express IFNAR; whereas all of the T cells will be WT or IFNAR-/-, respectively. By challenging these chimeric mice with Mtb, we can ascertain whether type I IFN signaling by T cells is required for host resistance. Summary. Our in vitro and in vivo models will determine how type I IFN affects T cell immunity to Mtb. We expect that these experiments will explain why type I IFN is detrimental to the host during chronic TB and may suggest how type I IFN signaling can be manipulated to treat TB, particularly for drug-resistant cases. PUBLIC HEALTH RELEVANCE: Pulmonary tuberculosis, the disease caused by Mycobacterium tuberculosis, is a threat to global health. Infection is usually asymptomatic because the immune system is able to limit bacterial growth. The disease tuberculosis occurs when the immune system is no longer able to contain the infection. This research proposal seeks to determine why type I interferon, a cytokine that is crucial during immunity to many pathogens, is detrimental to host resistance against M. tuberculosis. We hypothesize that type I interferon impairs T cell mediated immunity. We hope by understanding what features of the immune response are detrimental, as well as those that are beneficial, we can better develop interventions, including vaccination and immunomodulation, that will help prevent or treat tuberculosis.