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

描述(申请人提供)：结核分枝杆菌(Mtb)，本提案的焦点，是一种成功的人类病原体，通过多种机制颠覆和逃避宿主免疫。作为对感染的反应，天然免疫系统的细胞产生IL-12和I型干扰素(干扰素)。干扰素是一类具有多种活性的细胞因子家族。 在调节免疫和调节对病原体的保护方面。虽然IL-12对人类和啮齿动物的抗分枝杆菌免疫是必不可少的，但I型干扰素对宿主对结核病的免疫是有害的。重要的是，已经定义了“结核病特征”，将活动性结核病患者与潜伏感染的患者区分开来。其特征主要是由中性粒细胞驱动的干扰素诱导的基因图谱。免疫系统中几乎没有几个成分会对结核杆菌的抵抗力产生不利影响。为什么I型干扰素会对结核分枝杆菌的免疫产生不利影响，这是未知的，也是这项提案的重点。I型干扰素在急性病毒感染过程中调节NK和CD8+T细胞的激活、扩增和效应功能。我们推测，I型干扰素对结核分枝杆菌免疫的不利影响是通过抑制T细胞反应来实现的。战略。INKT细胞位于先天免疫和获得性免疫的交界处，具有NK细胞和传统T细胞的共同特征。我们的数据显示，干扰素？显著抑制IL-12和TCR驱动的干扰素？由iNKT细胞产生。INKT细胞具有天生的识别结核杆菌感染的巨噬细胞并限制细菌生长的能力。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细胞对于结核分枝杆菌的免疫是必不可少的，可能是因为它们在体内变得无能。相反，它们的特异性激活可以延长结核分枝杆菌感染后的存活时间。在目标1中，我们将使用来自I型干扰素受体(IFNAR)基因敲除或WT小鼠的巨噬细胞和iNKT细胞来确定结核分枝杆菌感染细胞产生的I型干扰素如何影响iNKT细胞功能。在目标2中，我们将确定I型干扰素在体内如何影响T细胞对结核分枝杆菌的免疫。将使用混合骨髓(BM)嵌合小鼠，以便可以并行研究暴露在相同细菌负载和炎症环境中的IFNAR-/-和WT T细胞。利用这些混合的骨髓嵌合小鼠，我们将确定在结核分枝杆菌感染期间，T细胞发出的I型干扰素信号如何影响它们的扩张、存活和效应功能的获得。另一组混合嵌合小鼠将用于确定T细胞发出的I型干扰素信号是否影响宿主对结核分枝杆菌感染的抵抗力。嵌合小鼠将使用90%的TCR？-/-BM和10%的WT或IFNAR-/-BM。这些小鼠中几乎所有的B细胞、巨噬细胞和DC都将表达IFNAR，而所有的T细胞将分别为WT或IFNAR-/-。通过用结核分枝杆菌攻击这些嵌合小鼠，我们可以确定宿主抵抗是否需要T细胞发出I型干扰素信号。总结。我们的体外和体内模型将确定I型干扰素如何影响T细胞对结核分枝杆菌的免疫。我们预计这些实验将解释为什么I型干扰素在慢性结核病期间对宿主有害，并可能建议如何操纵I型干扰素信号来治疗结核病，特别是对于耐药病例。

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.