Innate immune defense against community associated methicillin-resistant S.aureus

描述（由申请人提供）：这项竞争性更新申请将测试关于人类多形核白细胞（PMN）与摄入的金黄色葡萄球菌（SA）之间相互作用的三个新假设，以及它们对人类PMN、SA感染和炎症命运的影响。大量摄取的SA在PMN中存活，并促使PMN启动细胞命运程序，导致非典型凋亡。这些凋亡的，带有sa的PMN通过不完全明确的机制结合巨噬细胞（Mf），扭曲Mf细胞因子谱，并阻断efferocytosis。未被Mf内化的SA负载的PMN会发生坏死细胞死亡和裂解，从而释放出可存活的SA，这些SA通过PMN后毒性更强。在我们对PMN中杀微生物事件的新颖综合观点的框架内，我们将确定介导其在PMN中存活的SA的转录反应，定义由PMN响应活的细胞内SA启动的信号通路，这些细胞内SA触发了在SA感染的PMN中看到的非典型和最终的坏死细胞死亡。最后，我们将确定Mf清除PMN-SA失败的机制基础和后果，以及Mf摄取可存活SA持续存在的PMN的扭曲细胞因子谱。后一项研究将为SA如何破坏通常以炎症解决和恢复组织稳态为高潮的细胞事件提供重要的见解。每一个相互关联但又独立的目标都有强有力的初步数据支持。我们将确定SA对HOCl和其他PMN产生的毒素的上调msrA1/B、YjiE和其他转录反应如何促进SA的存活（1. a .i . iii）以及对PMN和Mf的功能影响（1.B.）。目的2：确定SA感染期间PMN和Mf功能变化的机制。我们将识别信号通路并确定PMN-SA“非典型”凋亡的分子基础（2. a）。——专注于Mcl-1 （2.A）。i), IL-1b (2.A.；ii)和HIF-1a (2.A。iii) - Mf减少PMN-SA的胞吐作用及其对促进炎症的影响(2)。B)， PMN-SA最终坏死细胞死亡（2.C）。我们的研究将确定PMN非典型凋亡和坏死死亡的机制，从而为吞噬细胞控制炎症反应的基本方面提供新的见解。从微生物的角度来看，我们将确定PMN暴露诱导存活的SA的转录适应的功能后果，从而深入了解SA的脆弱性，可以作为治疗攻击的新靶点。

DESCRIPTION (provided by applicant): This competitive renewal application will test three novel hypotheses about the interactions between human polymorphonuclear leukocytes (PMN) and ingested Staphylococcus aureus (SA) and their implications for the fate of human PMN, SA infection and inflammation. A significant fraction of ingested SA survives in PMN and prompts PMN to initiate cell fate programs that result in atypical apoptosis. These apoptotic, SA-laden PMN bind to macrophages (Mf), skew Mf cytokine profiles, and block efferocytosis, by incompletely defined mechanisms. SA-laden PMN not internalized by Mf undergo necrotic cell death and lysis, thereby releasing viable SA that are more virulent after passage through PMN. Within the framework of our novel, integrated view of microbicidal events in PMN, we will determine the transcriptional responses of SA that mediate their survival in PMN, define signaling pathways initiated by PMN in response to viable intracellular SA that trigger the atypical and eventual necrotic cell death seen in SA-infected PMN. Lastly, we will determine the mechanistic basis for and consequences of the failure of Mf to clear PMN-SA and the skewed cytokine profile of Mf that ingest PMN in which viable SA persist. The latter studies will provide important insight into how SA undermine cellular events that normally culminate in resolution of inflammation and return to tissue homeostasis. Each of the inter-related but independent aims is supported by strong preliminary data. Aim 1 Determine the mechanisms and consequences of survival of SA in human PMN phagosomes We will determine how SA upregulation of msrA1/B, YjiE, and other transcriptional responses to HOCl and other PMN- generated toxins promote SA survival (1.A.i-iii) and the functional consequences to PMN and Mf (1.B.). Aim 2 Determine mechanisms for functional changes in PMN and Mf during SA infection We will identify the signalling pathways and determine the molecular basis for "atypical" apoptosis of PMN-SA (2.A.) -- focusing on Mcl-1 (2.A.i), IL-1b (2.A.ii), and HIF-1a (2.A.iii) -- the decreased efferocytosis of PMN-SA by Mf and its impact on promoting inflammation (2.B), and the eventual necrotic cell death of PMN-SA (2.C). Our studies will identify mechanisms responsible for the atypical apoptosis and necrotic death of PMN, thereby providing novel insights into fundamental aspects of phagocyte control of the inflammatory response. From the microbial perspective, we will identify the functional consequences of transcriptional adaptations of surviving SA that were induced by PMN exposure, thus providing insight into SA vulnerability that could be exploited as novel targets for therapeutic attack.