Autophagy proteins in the immune response to Mycobacterium tuberculosis infection

项目摘要/摘要 结核分枝杆菌(Mtb)感染每年导致的死亡人数比任何其他单一感染源都要多。两者都有 结核病的疾病结果和病理是由宿主体内的免疫反应驱动的，这是 由参与先天免疫和获得性免疫的细胞之间的相互作用决定。因为它的关键作用 在结核病的免疫反应方面，人们对开发利用免疫的免疫疗法越来越感兴趣 控制感染的反应。特别是，刺激自噬来控制结核分枝杆菌感染是有兴趣的。 自噬在控制结核分枝杆菌感染中的作用是基于观察到Atg5fl/fl-LysM-cre小鼠 缺乏ATG5的单核细胞和中性粒细胞(中性粒细胞，PMN)会屈服于Mtb 30天后，出现与缺乏干扰素-γ信号的小鼠相似的极其严重的表型。ATG5是一个必不可少的 自噬蛋白和该领域的教条是在巨噬细胞中需要ATG5来靶向Mtb 溶酶体通过巨型自噬降解。与预期相反，我们已经证明了ATG5是 控制结核分枝杆菌感染所需的髓系细胞，这是由于一种不依赖于自噬的调节功能 炎症以中性粒细胞为主。此外，使用有条件地仅在PMN中缺失ATG5的小鼠(Atg5fl/fl- Mrp8-cre)，我们已经证明，中性粒细胞中ATG5的缺失可以导致对结核分枝杆菌感染的易感性，揭示了一种 PMN在结核分枝杆菌感染过程中ATG5的内在作用因此，更好地了解以下方面的角色非常重要 自噬蛋白在宿主防御中的作用，以了解干预时可能发生的影响范围 宿主导向疗法的自噬通量。我们对Atg5fl/fl-LysM-cre小鼠结核分枝杆菌发病机制的剖析 揭示了ATG5在感染期间在髓系细胞中发挥作用的多个阶段。在结核分枝杆菌感染期间，早期- 感染ATG5-/-细胞过度产生细胞因子和趋化因子，使PMN进入Atg5fl/fl-LysM-cre的肺内 小鼠的数量高于对照组小鼠。应答的ATG5-/-PMN放大促炎信号 而且ATG5-/-PMN的一个子集没有从肺中清除，我们预测这是由于PMN的缺陷造成的 凋亡的中性粒细胞发生凋亡和/或泡腾。凋亡的结核分枝杆菌感染的PMN的效应很重要 用于高效的抗原呈递。事实上，在清算ATG5-/-PMN方面的缺陷与延迟贩运有关 T细胞进入肺部。基于这些初步数据，我假设ATG5在多发性骨髓细胞中发挥作用 Mtb感染过程中的细胞，包括PMN中不依赖于自噬的功能，以及这些功能的共同作用 ATG5的表达可控制结核分枝杆菌的发病。为了检验这一假设，我将确定 髓系细胞ATG5缺失如何导致PMN聚集并阻止保护性获得性免疫 通过追求以下目标来回应Mtb：1)剖析ATG5在调节PRO-2生产中的作用 感染过程中的炎症信号，2)确定ATG5在调节中性粒细胞聚集和清除中的作用 在结核分枝杆菌感染过程中，3)确定髓系细胞中ATG5的丢失如何影响对结核分枝杆菌的适应性免疫反应。

PROJECT SUMMARY/ABSTRACT Mycobacterium tuberculosis (Mtb) infection kills more people a year than any other single infectious agent. Both the disease outcome and the pathology of TB are driven by the immune response mounted in the host, which is dictated by interactions between cells involved in innate and adaptive immunity. Because of the pivotal role of the immune response in TB, there is a growing interest in developing immunotherapies that harness the immune response to control the infection. In particular, there is interest in stimulating autophagy to control Mtb infection. The role of autophagy in controlling Mtb infection was based on the observation that Atg5fl/fl-LysM-cre mice lacking Atg5 in monocyte-derived cells and neutrophils (polymorphonuclear cells, PMN) succumb to Mtb within 30 days, an extremely severe phenotype similar to mice lacking IFN-γ signaling. Atg5 is an essential autophagy protein and the dogma in the field was that Atg5 was required in macrophages to target Mtb for lysosomal degradation through macroautophagy. Contrary to expectation, we have demonstrated that Atg5 is required in myeloid cells to control Mtb infection due to an autophagy-independent function that regulates PMN-dominated inflammation. In addition, using mice that conditionally delete Atg5 only in PMN (Atg5fl/fl- MRP8-cre), we have shown that loss of Atg5 in PMNs can result in susceptibility to Mtb infection, revealing a PMN intrinsic role for Atg5 during Mtb infection. Therefore, it will be important to better understand the roles for autophagy proteins in host defense to understand the scope of effects that may occur while intervening with autophagic flux with host-directed therapies. Our dissection of Mtb pathogenesis in Atg5fl/fl-LysM-cre mice has revealed multiple stages where Atg5 functions in myeloid cells during infection. During Mtb infection, an early- infected Atg5-/- cell overproduces cytokines and chemokines that bring PMN into the lungs of Atg5fl/fl-LysM-cre mice in higher numbers than in control mice. The responding Atg5-/- PMN amplify the pro-inflammatory signals and a subset of Atg5-/- PMN are not cleared from the lung, which we predict occurs due to a defect in PMN apoptosis and/or efferocytosis of the apoptotic PMN. Efferocytosis of apoptotic Mtb-infected PMN is important for efficient antigen presentation. Indeed, the defect in clearing Atg5-/- PMN correlates with delayed trafficking of T cells to the lungs. Based on these preliminary data, I hypothesize that Atg5 plays roles in multiple myeloid cells during Mtb infection, including an autophagy-independent function in PMN, and together these functions of Atg5 lead to control of Mtb pathogenesis. To test this hypothesis, I will determine the mechanistic basis for how loss of Atg5 in myeloid cells leads to PMN accumulation and precludes a protective adaptive immune response to Mtb by pursuing the following aims: 1) Dissect the roles for Atg5 in regulating production of pro- inflammatory signals during infection, 2) Define the roles for Atg5 in regulating PMN accumulation and clearance during Mtb infection, 3) Determine how loss of Atg5 in myeloid cells affects adaptive immune responses to Mtb.