The vital role of T404 phosphorylation of STAT2 in post-viral bacterial pneumonia

项目总结 病毒相关性细菌性肺炎是大流行中的主要死亡原因。因为我们使用不同的策略 为了对抗病毒和细菌，宿主的天然免疫反应在这两种类型的 感染同时发生，导致病毒后细菌性肺炎的死亡率较高。确定 初始病毒感染中干扰后续抗菌反应的关键事件将指导治疗 治疗病毒感染后细菌性肺炎。STAT2作为干扰素-I信号通路的重要组成部分，在细胞周期调控中起着至关重要的作用。 抗病毒反应，但在抗菌反应中产生不利影响，但机制尚不清楚。我们 在病毒感染的刺激下，发现了一种新的STAT2的T404磷酸化，从而实现了一种有效的抗病毒 在被感染的细胞中的反应。这一建议为研究STAT2 T404磷酸化在细胞周期调控中的作用提供了新的线索。 从三个角度探讨病毒后细菌性肺炎的发病机制：(1)干扰素的作用：对病毒的应答 感染时，干扰素-I的产生是为了限制病毒的传播，但在随后的细菌中具有神秘的功能 感染，由于抑制趋化因子的产生，IL-17依赖的免疫反应，以及募集 巨噬细胞。考虑到T404磷酸化在干扰素-I信号中的正向调节，STAT2将 损害病毒后细菌性肺炎的肺屏障的完整性；(2)炎症的调节： 我们报道，STAT2的存在增加了IL-6和其他依赖于NF-kB的细胞因子的产生 炎性细胞因子对内毒素的反应。这部分细胞因子会导致炎症相关的肺损伤。 与这一发现一致，我们的初步数据显示，STAT2 T404磷酸化缺陷小鼠 与野生型兄弟姐妹相比，它们不会受到内毒素的挑战。(3)刺激性抗菌作用 巨噬细胞的功能：通过检测细菌衍生的环二核苷酸，STING介导抗菌作用 巨噬细胞的功能，包括细胞因子的产生和细菌消化。我们发现T404 磷酸化介导STAT2在STING激活中的普遍功能，包括重塑STING- 介导的致炎基因表达，并抑制随后的结果，包括细菌 通行证。综上所述，我们认为STAT2的T404磷酸化是病毒诱导的一个关键事件 感染，增强了干扰素-I依赖的信号，夸大了炎症相关的急性肺 在继发性细菌性肺炎中，巨噬细胞的抗菌功能受到损害。这 提案将把我们的理解从结构和机制分析向前推进到表型变化 在体外和体内。我们还将测定T404磷酸化STAT2在小鼠体内的动力学。 铜绿假单胞菌肺炎，并在ARDS患者的巨噬细胞中验证这一发现- 相关性肺炎。本提案的成功完成将提供对这些监管机构的独特见解 过程和指导未来的治疗，特别是调节T404的磷酸化和刺痛功能，在 治疗病毒感染后细菌性肺炎。

PROJECT SUMMARY Virus-associated bacterial pneumonia is a leading cause of death in pandemics. Since we use different strategies to fight viruses and bacteria, host innate immune responses are confused and impaired when both types of infection occur simultaneously, resulting in higher mortality in post-viral bacterial pneumonia. Determining the key events in the initial viral infection that disturb the subsequent antibacterial responses will guide therapies in treating post-viral bacterial pneumonia. STAT2, as a critical component of IFN-I signaling, is essential for the antiviral response, but elicits detrimental effects in antibacterial response though yet-unknown mechanisms. We discovered a novel T404 phosphorylation of STAT2, stimulated by virus infections, enabling an efficient antiviral response in infected cells. This proposal sheds new light on the role of STAT2 T404 phosphorylation in the pathogenesis of post-viral bacterial pneumonia from three perspectives: (1) the action of IFN: In response to viral infection, IFN-I is produced to limit viral dissemination, but with enigmatic functions in the subsequent bacterial infection, due to suppressing chemokine production, IL-17-dependent immune responses, and recruitment of macrophages. Considering the positive regulation of T404 phosphorylation in IFN-I signaling, STAT2 will compromise the integrity of lung barriers in post-viral bacterial pneumonia; (2) the regulation of inflammation: We reported that the presence of STAT2 augments the production of IL-6 and other NF-kB-dependent inflammatory cytokines in response to LPS. This subset of cytokines drives inflammation-associated lung injury. In agreement with this finding, our preliminary data show that STAT2 T404 phosphorylation-deficient mice are protected from a challenge with LPS, compared with wild-type siblings. (3) STING-mediated antibacterial functions of macrophages: By detecting bacterial-derived cyclic dinucleotides, STING mediates the antibacterial functions of macrophages, including cytokine production, and bacterial digestion. We found that T404 phosphorylation mediates pervasive functions of STAT2 in STING activation, including reshaping STING- mediated gene expression to a pro-inflammatory profile, and inhibiting subsequent outcomes, including bacterial clearance. In summary, we propose that T404 phosphorylation of STAT2 is a key event, induced by virus infection, that enhances IFN-I-dependent signaling, exaggerates inflammatory-associated acute lung injury, and compromises antibacterial functions of macrophages in secondary bacterial pneumonia. This proposal will carry our understanding from structural and mechanistic analyses forward to phenotypic changes in vitro and in vivo. We will also determine the kinetics of T404 phosphorylation of STAT2 in mice with post- influenza P. aeruginosa pneumonia, and validate the findings in macrophages from patients with ARDS- associated pneumonia. Successful completion of this proposal will provide a unique insight into these regulatory processes and guide future therapies, especially modulating T404 phosphorylation and STING function, in treating post-viral bacterial pneumonia.