STAPHEX II: Dissecting Staphylococcus aureus macrophage exit

STAPHEX II：解剖金黄色葡萄球菌巨噬细胞出口

• 批准号: 446507619
• 负责人: Professor Dr. Alexander Weber, Ph.D.
• 金额: --
• 依托单位: Abteilung Immunologie
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/446507619?language=en
• 关键词: STAPHEX; II; Dissecting; Staphylococcus; aureus

Nasal carriage of Staphylococcus aureus is a major risk factor for severe and invasive infections. Clinical infection relapse even after state-of-the-art antibiotic therapy is not uncommon, suggesting that bacteria may hide inside cells. Recent studies in murine experimental models indicate that S. aureus persistence in intracellular reservoirs in macrophages in the liver or the peritoneum is critical for the pathology of sepsis development. During chronic infections such as osteomyelitis, S. aureus may also persist within cells for prolonged time. On a molecular and cellular level S. aureus dissemination and host cell exit or persistence are not well understood. After entering the bloodstream, S. aureus is readily phagocytosed by multiple types of phagocytes, e.g. macrophages. However, the pathogen is able to survive within human macrophages and escape from within. We could previously show that phenol soluble modulins (PSMs) and human-specific two component leukocidins LukAB and/or PVL are crucial for this process. PSMs can lyse cells receptor-independently, mediate the escape of S. aureus from phagosomes into the cytosol and function in mouse and humans. Conversely, LukAB and PVL are highly receptor dependent and restricted to humans, hampering analysis of these toxins in conventional mouse models. Our data indicate that LukAB promotes human macrophage escape and cell death in a non-conventional manner: although the NLRP3 inflammasome is activated resulting in IL-1beta release, pyroptosis or apoptosis are not involved; rather MLKL/necroptosis features are activated but are not sufficient for toxin-dependent cell death and exit. Using novel genetically labeled bacteria and cell lines features of exit can be monitored and may involve direct spread to uninfected macrophages by efferocytosis. In good agreement with the SPP’s key aims three resulting questions will be addressed here: 1) Which mechanisms induced by LukAB in ExitStaph synergize with MLKL or act independently? How is the host cell reprogrammed? 2) Is the activity of LukAB from within strictly dependent on classical CD11b binding and/or signaling or involves other bacterial and/or host factors? 3) Does cell-to-cell spread involve bona fide exit and release of free bacteria from cells for subsequent re-infection or does it rather entail uptake of bacteria in combination with cellular debris (efferocytosis)? What are the differences of the two alternative routes of bacterial transfer? By combining our expertise in the molecular and cellular immune cell signaling (Weber) and S. aureus physiology and genetic engineering (Wolz), we will define the key determinants driving cell death or S. aureus persistence. Understanding the mechanisms employed by S. aureus to evade intracellular killing, survive and escape could pave the way for better classification and treatment of clinical S. aureus phenotypes using novel anti-infective treatment approaches.

鼻腔携带金黄色葡萄球菌是严重和侵入性感染的主要危险因素。即使在最先进的抗生素治疗后，临床感染复发也并不罕见，这表明细菌可能隐藏在细胞内。最近在小鼠实验模型中的研究表明，S。金黄色葡萄球菌在肝或腹膜中巨噬细胞的细胞内储库中的持续存在对于脓毒症发展的病理学是至关重要的。在慢性感染如骨髓炎，S。金黄色葡萄球菌也可以在细胞内持续延长的时间。在分子和细胞水平上S。金黄色葡萄球菌的播散和宿主细胞的退出或持久性还不清楚。S.金黄色葡萄球菌容易被多种类型的吞噬细胞例如巨噬细胞吞噬。然而，病原体能够在人类巨噬细胞内存活并从内部逃逸。我们先前可以表明，苯酚可溶性调节蛋白（PSM）和人类特异性双组分杀白细胞素LukAB和/或PVL是这个过程的关键。PSMs能不依赖受体地裂解细胞，介导S.金黄色葡萄球菌从吞噬体进入胞质溶胶，并在小鼠和人类中发挥作用。相反，LukAB和PVL是高度受体依赖性的，并且仅限于人类，阻碍了在常规小鼠模型中对这些毒素的分析。我们的数据表明，LukAB以非常规方式促进人巨噬细胞逃逸和细胞死亡：尽管NLRP 3炎性体被激活导致IL-1 β释放，但不涉及细胞凋亡或细胞凋亡;相反，MLKL/坏死性凋亡特征被激活，但不足以导致毒素依赖性细胞死亡和退出。使用新的基因标记的细菌和细胞系的出口功能可以监测，并可能涉及直接传播到未感染的巨噬细胞通过巨噬细胞。与SPP的关键目标完全一致，这里将解决三个由此产生的问题：1）在ExitStaph中LukAB诱导的机制与MLKL协同作用或独立作用？宿主细胞是如何重新编程的？2)来自内部的LukAB活性是否严格依赖于经典的CD 11b结合和/或信号传导，或涉及其他细菌和/或宿主因子？3)细胞间的传播是否包括真正的退出和释放游离细菌从细胞中随后的再感染，或者它是否需要吸收细菌与细胞碎片（胞饮症）？两种不同的细菌转移途径有什么区别？通过结合我们在分子和细胞免疫细胞信号传导（韦伯）和S。金黄色葡萄球菌生理学和遗传工程（Wolz），我们将定义驱动细胞死亡或S。金黄色持久性理解S.金黄色葡萄球菌逃避胞内杀伤、存活和逃逸的能力，为临床上更好的分型和治疗奠定了基础。金黄色葡萄球菌表型使用新的抗感染治疗方法。