Anaplasma regulation of host granulocyte functions

描述（由申请方提供）：人粒细胞无形体病（HGA，以前称为HGE）是一种由嗜吞噬细胞无形体（嗜中性粒细胞的专性细胞内寄生虫）引起的新发蜱媒感染。患者发展为“流感样”疾病，严重时可伴有休克或呼吸窘迫。死亡是罕见的，但异常的宿主免疫和炎症可导致机会性感染。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，有利于受感染的细胞积累和杀微生物和调节能力的丧失。感染的中性粒细胞减少了一些宿主基因的转录效应机制和细胞周期。A.嗜吞噬细胞菌AnkA蛋白从寄生虫空泡中转运到宿主细胞核中积累，在那里它是唯一已知的进入细胞的细菌蛋白。此外，AnkA结合宿主DNA和蛋白质，并且特别结合已知显著影响染色体上50至100 kb内基因转录的基质附着区。因此，我们建议AnkA： 1.快速转录并转运至粒细胞核; 2.介导A.嗜吞噬细胞菌感染; 3.直接与宿主细胞染色质相互作用以影响宿主基因的转录。 我们建议i）描述ankA转录和表达的动力学，并检查是否有其他基因在A. ii）表征AnkA对中性粒细胞功能的影响; iii）证明A.嗜吞噬细胞噬菌体感染或AnkA通过AnkA与特化的ATC染色质结构结合、染色质结构的修饰和特定基因座处基因转录的改变（特别强调CYBB、RAC 2和IL 8）来影响关键基因的转录和中性粒细胞功能。 因此，我们将评估A.嗜吞噬细胞菌和AnkA调节基因转录并因此调节中性粒细胞功能。所提出的控制模型尚未描述任何细菌，将提供一种新的机制，细菌控制感染的主机。这些研究将为理解细菌如何生活在中性粒细胞中并破坏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。随着这将是一个战略的设计预防，管理和治疗HGA，和一个新的模型，研究中性粒细胞生物学。

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.