Subverted host cell signaling by AnkA in Anaplasma phagocytophilum infection

描述（由申请人提供）：嗜吞噬细胞无原体，是一种感染中性粒细胞并引起人粒细胞性埃利希体病的人类病原体。在美国，它是第二大最常见的蜱虫相关感染，仅次于莱姆病。虽然嗜中性粒细胞杀灭细菌非常有效，但嗜吞噬细胞芽胞杆菌是一个例外，因为它不仅逃脱了嗜中性粒细胞的杀灭，而且在嗜中性粒细胞中生存和复制。嗜吞噬细胞干扰超氧化物介导的杀伤和延迟中性粒细胞凋亡。人们对嗜吞噬细胞芽胞杆菌如何完成这些主要壮举知之甚少。本研究旨在确定嗜吞噬细胞芽胞杆菌操纵这些细胞过程的基本机制。我们最近在嗜吞噬胞杆菌中鉴定出的第一个细菌毒力因子AnkA可能在操纵中性粒细胞功能中起关键作用。因此，嗜吞噬芽胞杆菌感染中性粒细胞为研究中性粒细胞生物学和细菌杀伤途径提供了理想的模型。总体假设是易位AnkA干扰宿主中性粒细胞的信号通路，抑制超氧化物的产生，延缓细胞凋亡。细菌与宿主细胞结合后，AnkA被转运到宿主细胞质中，然后迅速酪氨酸磷酸化（在几秒到几分钟内）。酪氨酸磷酸化允许AnkA结合宿主细胞中关键信号蛋白的SH2结构域。此外，AnkA也可能通过SH3结构域和锚蛋白重复序列结合蛋白质。通过这些假定的蛋白质相互作用，AnkA可能改变宿主细胞信号传导并引起中性粒细胞的细胞变化。Aim 1旨在确定与AnkA结合的宿主细胞蛋白的特异性相互作用，Aim 2旨在研究AnkA在抑制中性粒细胞杀伤中的作用。目的3将探讨AnkA在延缓中性粒细胞凋亡中的作用。长期目标是：1)确定导致嗜吞噬芽胞杆菌在中性粒细胞中存活的机制，2)开发操纵中性粒细胞的新途径，从而导致炎症或感染的潜在新治疗方法，以及3)增强我们对中性粒细胞生物学的理解，因为它与免疫系统有关。公共卫生相关性：由嗜吞噬细胞绦虫引起的人类粒细胞性埃利希体病是美国第二大常见的蜱虫相关疾病。本研究旨在探讨嗜吞噬细胞芽胞杆菌如何在中性粒细胞中存活。这可能会导致更好地了解中性粒细胞在免疫系统中的功能，并可能导致潜在的炎症和感染的新疗法。

DESCRIPTION (provided by applicant): Anaplasma phagocytophilum, is a human pathogen that infects neutrophils and causes Human Granulocytic Ehrlichiosis. In the Unites States it is the second most common tick-associated infection, only surpassed by Lyme disease. Although neutrophils are very efficient in killing bacteria, A. phagocytophilum is the exception as it not only escapes killing by neutrophils, it lives and replicates inside neutrophils. A. phagocytophilum interferes with superoxide-mediated killing and delays neutrophil apoptosis. It is poorly understood how A. phagocytophilum accomplishes these major feats. This proposal seeks to identify the basic mechanism how A. phagocytophilum manipulates these cellular processes. Our recent identification of the first bacterial virulence factor in A. phagocytophilum, AnkA, may play a pivotal role in manipulating neutrophil functions. Consequently, A. phagocytophilum infection of neutrophils provides an ideal model to study the pathways involved in neutrophil biology and bacterial killing. The global hypothesis is that translocated AnkA interferes with host signaling pathways in the neutrophil, resulting in the inhibition of superoxide generation and the delay of apoptosis. Upon bacterial binding to the host cell, AnkA is translocated into the host cell cytoplasm and is then rapidly tyrosine phosphorylated (within seconds to minutes). Tyrosine phosphorylation allows AnkA to bind to SH2 domains of key signaling proteins in the host cell. Further, AnkA may also bind proteins via SH3 domains and ankyrin repeats. Through these putative protein interactions AnkA may alter host cell signaling and cause the cellular changes in neutrophils. Aim 1 seeks to identify the specific interactions of host cell proteins that bind to AnkA Aim 2 proposes to study the role of AnkA in inhibition of killing by the neutrophil. Aim 3 will examine the role of AnkA in the delay of neutrophil apoptosis. The long-term goals are: 1) the identification of the mechanism leading to survival of A. phagocytophilum in neutrophils, 2) the development new avenues to manipulate neutrophils, leading to potential new treatments of inflammation or infections, and 3) enhancement of our understanding of neutrophil biology as it relates to the immune system. PUBLIC HEALTH RELEVANCE: Human Granulocytic Ehrlichiosis, caused by A. phagocytophilum, is the second most common tick- associated disease in the United States. This proposal seeks to investigate how A. phagocytophilum can survive in neutrophils. This may lead to a better understanding of the function of neutrophils within the immune system and may lead to potential new treatments of inflammation and infections.