Innate immunity and inflammatory response of macrophages to Legionella infection

项目摘要 依赖于体外的信号，巨噬细胞可以经历短暂和可逆的分化 分为两个主要亚类：促炎性“M1”（经典活化）或抗炎性“M2” （交替激活）表型。巨噬细胞在体外暴露于高水平葡萄糖后 或在体内糖尿病患者中，它们经历分化和活化成M1促炎性细胞因子。 状态，通过代谢的细胞重编程介导产生促炎细胞因子 通过上调有氧糖酵解。巨噬细胞的M1促炎分化是 控制细菌感染的先天免疫反应的重要分支。我们的初步数据 表明当巨噬细胞吞噬细胞内病原体嗜肺军团菌时， (Lp)当它们被激活时，它们通过分化成活化的M1样促炎表型而迅速响应。 尽管这种快速的巨噬细胞促炎激活， (LCV)通过限制其与溶酶体的融合而绕过巨噬细胞活化。我们发现，早期 人单核细胞衍生的巨噬细胞（hMDM）向M1样促炎性分化 脂蛋白是一种先天性免疫反应的细胞溶质高葡萄糖产生的快速降解， 通过注射的军团菌淀粉酶（LamA）效应子来抑制糖原。我们发现LP已经进化出一种 通过注射MavE在促炎性hMDM内的溶酶体降解旁路途径 在LCV膜的胞质侧上的微结构域中定位。 mavE缺陷型突变体被hMDM靶向至溶酶体进行降解，并且突变体 在体外和体内都完全减毒。我们已经解决了新的三维晶体结构 的MavE，其显示了涉及NPxY真核基序的胞质表面暴露结构域 与磷酸酪氨酸结合衔接蛋白结合。我们的中心假设是：M1样亲- hMDM对Lp感染的炎性激活是对细胞溶质的先天性免疫应答， LamA引起的高血糖，病原体利用MavE绕过先天性免疫 巨噬细胞途径的溶酶体降解。为了检验这个假设，我们的具体目标是： 特定目的I：在HMD中hMDM的M1样促炎分化机制 对LamA效应的反应;和特定目标II：逃避先天免疫缺陷的机制。 通过利用溶酶体旁路的溶酶体降解的巨噬细胞功能 由MavE介导的通路。在完成我们建议的研究后，我们将发现 巨噬细胞对脂蛋白和溶酶体的先天促炎反应机制 降解旁路途径被病原体阻断，以避免致命的命运。

Project Summary Depending on the signals in vitro, macrophages can undergo transient and reversible differentiation into two main subsets: pro-inflammatory “M1” (classically activated) or anti-inflammatory “M2” (alternatively activated) phenotype. Upon exposure of macrophages to high levels of glucose in vitro or in diabetic patients in vivo, they undergo differentiation and activation into a M1 pro-inflammatory state, which produces pro-inflammatory cytokines mediated by cellular reprogramming of metabolism through upregulating aerobic glycolysis. The M1 pro-inflammatory differentiation of macrophages is an import arm of the innate immune response to control bacterial infections. Our preliminary data show that when macrophages engulf the intracellular bacterial pathogen Legionella pneumophila (Lp), they rapidly respond by differentiation into an activated M1-like pro-inflammatory phenotype. Despite this rapid macrophage pro-inflammatory activation, the Legionella-containing vacuole (LCV) bypasses macrophage activation by limiting its fusion to lysosomes. We show that the early M1-like pro-inflammatory differentiation of human monocytes-derived macrophages (hMDMs) to Lp is an innate immune response to cytosolic hyper-glucose generated through rapid degradation of glycogen by the injected Legionella amylase (LamA) effector. We discovered that Lp has evolved a lysosomal degradation bypass pathway within the pro-inflammatory hMDMs by injecting the MavE effector, which becomes localized in a micro-domain on the cytosolic side of the LCV membrane. The mavE-deficient mutant is targeted by hMDMs to the lysosomes for degradation, and the mutant is totally attenuated in vitro and in vivo. We have resolved the novel three dimensional crystal structure of MavE, which shows a cytosolic surface-exposed domain with an NPxY eukaryotic motif involved in binding to phosphotyrosine-binding adaptor proteins. Our central hypothesis is: the M1-like pro- inflammatory activation of hMDMs to Lp infection is an innate immune response to the cytosolic hyper-glucose elicited by LamA, and the pathogen utilizes MavE to bypass the innate immune macrophage pathway of lysosomal degradation. To test the hypothesis, our specific aims are: Specific Aim I: The mechanisms of M1-like pro-inflammatory differentiation of hMDMs in response to the effect of LamA; and Specific Aim II: The mechanisms of evasion of the innate macrophage function of lysosomal degradation through utilization of a lysosomes bypass pathway mediated by MavE. Upon completion of our proposed studies, we will discover the mechanism of the innate pro-inflammatory response of macrophages to Lp and the lysosomal degradation bypass pathway maneuvered by the pathogen to avoid a fatal fate.