Microbial Response to Neutrophil Phagocytosis

微生物对中性粒细胞吞噬作用的反应

• 批准号: 6729218
• 负责人: HENRY ROSEN
• 金额: $ 30.32万
• 依托单位: UNIVERSITY OF WASHINGTON
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-04-01 至 2007-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6729218
• 关键词: Escherichia coli; NAD(P)H dehydrogenase; bacterial RNA; bacterial genetics; chronic granulomatous disease; clinical research; gene expression; gene targeting; host organism interaction; human subject; messenger RNA; microarray technology; myeloperoxidase; neutrophil; phagocytosis; transcription factor

DESCRIPTION (provided by applicant): Neutrophils are a key component of host defense against bacterial and fungal pathogens. When neutrophils are severely diminished in number or function, the host becomes highly susceptible to serious infection. Neutrophils typically ingest and kill bacteria within a short space of time. In order to gain a better understanding of the bacterial response to phagocytosis, genomic arrays will be used to assess changes in mRNA abundance for Escherichia coli cells ingested by neutrophils. We expect to learn how ingested bacteria prioritize responses to stresses generated in the phagocyte and whether these responses enhance microbial survival. The effects of neutrophils deficient in antimicrobial systems mediated by the phagocyte NADPH oxidase (CGD, chronic granulomatous disease) or the enzyme myeloperoxidase will be compared with normal neutrophils. Initial studies indicate that normal neutrophils, but not CGD neutrophils, evoke an anti-oxidant response mediated by the bacterial transcription factor, OxyR. Disruption of the oxyR gene generated a bacterial strain that was 10-fold more susceptible to killing by normal neutrophils. The oxyR strain also appears to be markedly attenuated for virulence in a mouse model of ascending pyelonephritis. This proposal seeks to characterize oxyR effects more fully, and to explore the effects of selected other major transcriptional responses both to neutrophil phagocytosis and to isolated antimicrobial model systems. It also seeks to implement methodology that will emphasize detection of phagocytosis-induced changes for mRNA transcripts present in a pathogenic E. coli strain but not in a laboratory-adapted strain. The driving hypothesis for the latter goal being that: pathogen-specific transcripts contribute substantially to the pathogenic phenotype. Expression profiling of phagocytosed bacteria appears to provide useful information about conditions in the phagocytic vacuole and about important bacterial defenses mounted in response to this hostile environment.

描述（由申请人提供）：中性粒细胞是宿主防御细菌和真菌病原体的关键组成部分。当中性粒细胞的数量或功能严重减少时，宿主就变得非常容易受到严重感染。 中性粒细胞通常会在短时间内吞噬并杀死细菌。为了更好地了解细菌对吞噬作用的反应，基因组阵列将用于评估中性粒细胞摄入的大肠杆菌细胞的 mRNA 丰度变化。我们希望了解摄入的细菌如何优先考虑对吞噬细胞产生的压力的反应，以及这些反应是否能增强微生物的生存。吞噬细胞 NADPH 氧化酶（CGD，慢性肉芽肿病）或髓过氧化物酶介导的抗菌系统缺陷的中性粒细胞的影响将与正常中性粒细胞进行比较。初步研究表明，正常中性粒细胞（而非 CGD 中性粒细胞）会引起由细菌转录因子 OxyR 介导的抗氧化反应。 oxyR 基因的破坏产生了一种细菌菌株，该菌株对正常中性粒细胞的杀伤能力提高了 10 倍。 oxyR 菌株在上行性肾盂肾炎小鼠模型中的毒力似乎也明显减弱。 该提案旨在更全面地表征 oxyR 效应，并探索选定的其他主要转录反应对中性粒细胞吞噬作用和分离的抗菌模型系统的影响。 它还寻求实施强调检测致病性大肠杆菌菌株中存在的吞噬作用诱导的mRNA转录物变化的方法，而不是实验室适应菌株中的mRNA转录物变化。后一个目标的驱动假设是：病原体特异性转录物对致病表型有很大贡献。 吞噬细菌的表达谱似乎提供了有关吞噬液泡条件以及针对这种敌对环境而建立的重要细菌防御的有用信息。