Consequences of interactions between human neutrophils and Staphylococcus aureus

 描述(申请人提供)：人多形核白细胞(PMN)处于细胞天然免疫介导的宿主抵抗感染的第一线，尤其是由金黄色葡萄球菌(SA)等生物引起的感染。尽管PMN有强大的抗菌系统，但摄入的SA中仍有10%-20%在PMN中存活，但不能复制。金黄色葡萄球菌在中性粒细胞中的持续存在具有深远的临床后果，因为金黄色葡萄球菌感染的特征是复发、转移和对金黄色葡萄球菌敏感的抗生素失效。在我们对携带SA的人PMN的命运及其与单核细胞来源的巨噬细胞(M？)相互作用的持续研究中，我们有了一些新的发现：PMN-SA(1)吞噬SA后的早期表现出一种非典型的病原体诱导的细胞凋亡的表型；(2)M？不能有效地吞噬细胞；(3)维持增殖细胞核抗原(PCNA)的持续水平，这是一种在PMN细胞质中表达的细胞周期蛋白，最近与通过清除原酶来延长PMN存活有关；以及(4)以与坏死性下垂最为一致的方式进行裂解，这是一种caspase非依赖性的程序性坏死性细胞死亡途径，以前从未在PMN中描述过，但涉及一个多组分的细胞质信号复合体和依赖于受体相互作用的蛋白激酶1(RIP1K)。我们推断，PMN-SA和M？之间的这些细胞事件驱动了SA感染的临床特征，并建议进行研究，以探索我们新观察到的机制。目的1：确定PMN-SA泡腾失败的机制1A：确定PMN-SA产生的促进M？1B泡腾的信号：确定PMN-SA产生的积极阻断M？1C泡腾的信号：确定PMN-SA 1D攻击M？的信号通路和效应反应：确定PMN-SA产生的胞外体在M？调节泡腾作用中的作用目标2：确定细胞成分、生化事件、中性粒细胞-SA 2B中核糖体的组成和调节：确定增殖细胞核抗原在中性粒细胞-SA 2C最初延长存活和最终溶解中的作用：确定中性粒细胞-SA进入坏死下垂过程中的信号通路2D：确定肿瘤坏死因子依赖信号在中性粒细胞-SA坏死症中的作用我们的研究将确定中性粒细胞-SA的非典型凋亡、泡泡失败和坏死性死亡的机制，从而为炎症反应的吞噬细胞控制的基本方面和新的潜在治疗靶点提供新的见解。

 DESCRIPTION (provided by applicant): Human polymorphonuclear leukocytes (PMN) are at the front-line of cellular innate immune-mediated host defense against infection, especially those caused by organisms such as S. aureus (SA). Despite the potent PMN antimicrobial system, 10-20% of ingested SA remained viable, but not replicating, in PMN. Persistence of SA within PMN has profound clinical consequences, as signature features of staphylococcal infection are relapse, metastases, and failure of antibiotics to which SA are susceptible. In our ongoing studies of the fate of SA-laden human PMN and their interactions with monocyte-derived macrophages (MØ), we have made several novel findings: PMN-SA (1) early after phagocytosis of SA display a phenotype that is atypical for pathogen-induced apoptosis; (2) are not efficiently efferocytosed by MØ; (3) maintain sustained levels of proliferating cell nuclear antigen (PCNA), a cell-cycle protein expressed in PMN cytoplasm, and recently linked to prolonging PMN survival by scavenging procaspases; and (4) lyse in a fashion most consistent with necroptosis, a caspase-independent programmed necrotic cell death pathway never previously described in PMN but involving a multicomponent cytoplasmic signaling complex and dependence on receptor-interacting protein kinase 1 (RIP1K). We reason that these cellular events in and between PMN-SA and MØ drive the clinical hallmarks of SA infection and propose studies to explore of the mechanisms underlying our novel observations. Aim 1: Determine the mechanisms underlying the failed efferocytosis of PMN-SA by M¿ 1A: Identify signals generated by PMN-SA that promote efferocytosis by MØ 1B: Identify signals generated by PMN-SA that actively block efferocytosis by MØ 1C: Identify signaling pathways and effector responses of MØ challenged with PMN-SA 1D: Determine the role of ectosomes generated by PMN-SA to modulate efferocytosis by MØ Aim 2: Identify cellular components, biochemical events, and signaling pathways underlying necroptosis of PMN-SA 2A: Determine the composition and regulation of the ripoptosome in PMN-SA 2B: Determine the contribution of PCNA to the initial prolonged survival and eventual lysis of PMN-SA 2C: Determine the signaling pathways engaged as PMN-SA proceed to necroptosis 2D: Determine the role of TNF-dependent signaling in necroptosis of PMN-SA Our studies will identify mechanisms responsible for the atypical apoptosis, failed efferocytosis, and necrotic death of PMN-SA, thereby providing novel insights into fundamental aspects of phagocyte control of the inflammatory response and new potential therapeutic targets.