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

项目摘要 病毒相关性细菌性肺炎是大流行病中死亡的主要原因。因为我们使用不同的策略 为了对抗病毒和细菌，宿主的先天免疫反应被混淆和受损，当这两种类型的免疫反应都被破坏时， 感染同时发生，导致病毒感染后细菌性肺炎死亡率更高。确定 在最初的病毒感染中干扰随后的抗菌反应的关键事件将指导治疗， 治疗病毒感染后的细菌性肺炎STAT 2作为IFN-I信号传导的关键组分，对于IFN-γ和IFN-γ的表达是必不可少的。 抗病毒反应，但在抗菌反应中产生有害作用，尽管机制尚不清楚。我们 发现了一种新的STAT 2的T404磷酸化，由病毒感染刺激， 感染细胞的反应。这一提议为STAT 2 T404磷酸化在细胞凋亡中的作用提供了新的线索。 病毒感染后细菌性肺炎的发病机制从三个方面：（1）干扰素的作用：响应病毒感染， 感染时，产生IFN-I以限制病毒传播，但在随后的细菌感染中具有神秘的功能。 感染，由于抑制趋化因子的产生，IL-17依赖性免疫反应，和募集 巨噬细胞考虑到T404磷酸化在IFN-I信号传导中的正调节，STAT 2将 在病毒感染后细菌性肺炎中损害肺屏障的完整性;（2）炎症的调节： 我们报道了STAT 2的存在增加了IL-6和其他NF-kB依赖性细胞因子的产生。 炎症细胞因子对LPS的反应。这类细胞因子驱动炎症相关的肺损伤。 与这一发现一致，我们的初步数据显示STAT 2 T404磷酸化缺陷小鼠 与野生型同胞相比，保护免受LPS的攻击。(3)STING介导的抗菌 巨噬细胞的功能：通过检测细菌衍生的环状二核苷酸，STING介导了巨噬细胞的抗菌作用。 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STAT 2在STING激活中的普遍功能，包括重塑STING- 介导的基因表达，以促炎的概况，并抑制随后的结果，包括细菌 间隙总之，我们认为STAT 2的T404磷酸化是病毒诱导的一个关键事件， 感染，增强IFN-I依赖性信号传导，加重炎症相关急性肺 损伤，并损害继发性细菌性肺炎中巨噬细胞的抗菌功能。这 这项提案将使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。我们还将确定T404磷酸化的STAT 2在小鼠中的动力学， 流感铜绿假单胞菌肺炎，并验证ARDS患者巨噬细胞中的发现- 相关肺炎成功完成此提案将为这些监管提供独特的见解 过程和指导未来的治疗，特别是调节T404磷酸化和STING功能， 治疗病毒感染后的细菌性肺炎

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.