Anaplasma regulation of host granulocyte functions

描述(申请人提供)：人粒细胞无形体病(HGA，前身为HGE)是一种由嗜中性粒细胞专性细胞内寄生虫-吞噬无浆菌引起的新出现的扁虱传播感染。患者会患上一种类似流感的疾病，这种疾病可能会很严重，伴有休克或呼吸窘迫。死亡并不常见，但宿主免疫和炎症异常可导致机会性感染。受感染的中性粒细胞同时被“激活”和“失活”，导致不协调的促炎反应，有利于感染细胞的聚集和失去杀菌和调节能力。感染的中性粒细胞减少了一些宿主基因的转录，这些基因用于效应机制和细胞周期。吞噬细胞菌Anka蛋白是从寄生液泡中转运到宿主细胞核中积累的，是已知的唯一进入细胞的细菌蛋白。此外，ANKA结合宿主DNA和蛋白质，并特别结合到已知显著影响染色体上50-100 kb基因转录的基质附着区。因此，我们建议安卡： 1.被快速转录并运输到粒细胞核； 2.吞噬弧菌感染可介导部分中性粒细胞功能改变； 3.直接与宿主细胞染色质相互作用，影响宿主基因的转录。 我们建议：1)描述ANKA转录和ANKA表达的动力学，并研究吞噬细胞性嗜血杆菌基因组中靠近ANKA的其他基因是否受到协调调控；II)表征ANKA对中性粒细胞功能的影响；III)展示吞噬细胞性嗜血杆菌感染或ANKA如何通过ANKA与特定的ATC染色质结构结合、染色质结构的改变以及特定基因座上基因转录的变化来影响关键基因的转录和中性粒细胞的功能，特别是对CYBB、RAC2和IL8的影响。 因此，我们将评估吞噬细胞性假单胞菌和ANKA如何调节基因转录，从而调节中性粒细胞的功能。所提出的控制模式尚未对任何细菌进行描述，并将为细菌控制受感染宿主提供一种新的机制。这些研究将为了解细菌如何生活在中性粒细胞中并颠覆中性粒细胞提供一个模型，并应提高对疾病发病机制的理解。随之而来的是预防、管理和治疗HGA的设计策略，以及研究中性粒细胞生物学的新模型。

DESCRIPTION (provided by applicant): Human granulocytic anaplasmosis (HGA, formerly HGE) is an emerging tick-borne infection caused by Anaplasma phagocytophilum, an obligate intracellular parasite of neutrophils. Patients develop a "flu-like" illness that can be severe with shock or respiratory distress. Death is infrequent, but abnormal host immunity and inflammation can lead to opportunistic infections. Infected neutrophils are simultaneously "activated" and "deactivated" resulting in a discoordinated proinflammatory response favoring infected cell accumulation and loss of microbicidal and regulatory capacity. Infected neutrophils have diminished transcription of some host genes for effector mechanisms and cell cycling. A. phagocytophilum AnkA protein is ferried from the parasitophorous vacuole to accumulate in the host cell nucleus, where it is the only known protein of the bacterium to enter the cell. Moreover, AnkA binds both host DNA and proteins, and binds particularly to matrix attachment regions that are known to significantly influence transcription of genes within 50 to 100 kb on the chromosome. Thus, we propose AnkA: 1. is rapidly transcribed and transported to the granulocyte nucleus; 2. mediates some of the neutrophil functional changes with A. phagocytophilum infection; 3. directly interacts with host cell chromatin to influence the transcription of host genes. We propose to i) describe the kinetics of ankA transcription and AnkA expression, and to examine whether other genes in proximity to ankA in the A. phagocytophilum genome are coordinately regulated; ii) characterize the effects of AnkA on neutrophil function; iii) demonstrate how A. phagocytophilum infection or AnkA affect transcription of key genes and neutrophil function by AnkA binding to specialized ATC chromatin structures, modification of chromatin architecture and change in gene transcription at specific loci, with special emphasis on CYBB, RAC2, and IL8. Thus, we will evaluate how A. phagocytophilum and AnkA regulate gene transcription and consequently neutrophil function. The proposed model of control is not yet described for any bacterium and would provide a novel mechanism for bacterial control of infected hosts. These studies will provide a model for understanding how the bacterium lives in and subverts neutrophils and should improve comprehension of disease pathogenesis. With this will come a strategy for design of prevention, management, and treatment of HGA, and a new model for investigating the neutrophil biology.