Aberrant immune activation in the tuberculosis granuloma: a pivotal role in necrosis

肺内结核肉芽肿的坏死是一种高度进化的毒力策略，对 M.tb.变速箱。了解这一过程对于合理设计拼命的 结核病所需的疫苗和治疗方法。结核分枝杆菌通过触发先天因子诱导干扰素β分泌 胞浆监视途径(CSP)，而且越来越清楚的是这种I型干扰素(IFN-I) 应对措施在宿主控制结核病方面起着不利作用。我们已经确定sst1基因 结核肉芽肿中的坏死灶在巨噬细胞偶联中起重要作用 通过干扰素-I反应发出压力信号。我们认为，CSP的病原体触发 当异常的宿主反应持续时，启动干扰素-I驱动的过度炎症 导致坏死的。在这项建议中，我们将评估结核病的发病机制作为组织反应。 出了问题，而不是传统的细胞只关注巨噬细胞。我们的目标是： 1.剖析干扰素-I反应与综合应激反应(ISR)的联系机制 在体外用肿瘤坏死因子α刺激的易感巨噬细胞中的信号，我们将鉴定干扰素-I- 在sst1S观察到的导致凋亡前状态(PAS)的应激依赖机制 确定PAS如何影响巨噬细胞与结核分枝杆菌的相互作用，以及PAS是否 抑制剂可以改善结核分枝杆菌的控制和/或巨噬细胞的存活。 2.确定干扰素-I途径在巨噬细胞应激信号和坏死中的作用 在活体肺结核肉芽肿中，我们将确定结核坏死的早期生物标志物。 并确定哪种干扰素-I依赖途径在肉芽肿中起主导作用 在B6-sst1S小鼠中引入IFNAR1和IRF3基因敲除突变导致的坏死化。 3.确定结核分枝杆菌调节的环二核苷酸(CDN)水平在调节宿主中的作用 巨噬细胞应激信号、死亡和肉芽肿内坏死，我们将使用一组 结核分枝杆菌突变株诱导不同水平的c-di-AMP和cGAMP以确定它们如何 体外控制巨噬细胞干扰素-I和细胞死亡途径，体内控制肉芽肿坏死。 4.利用小分子靶向体内肉芽肿坏死机制的研究 在没有免疫抑制的情况下预防免疫病理，我们将利用我们的 开发新的坏死性肉芽肿导向疗法以阻断异常宿主的发现 在易受感染的宿主中引起坏死的反应。我们设想这些疗法将会纠正 非全身性抑制的结核肉芽肿中的干扰素-I激活和坏死性炎症 抗结核免疫。这种方法对于治疗多药耐药尤其重要。 结核分枝杆菌的各种形式，在保护宿主免疫力的同时，减少肺损伤是必不可少的。

Necrosis of TB granulomas in the lung is a highly evolved virulence strategy, pivotal for M.tb. transmission. Understanding this process is essential for rational design of desperately needed vaccines and therapeutics for TB. M.tb elicits IFNβ secretion by triggering the innate cytosolic surveillance pathway (CSP), and it is increasingly clear that this type I IFN (IFN-I) response plays detrimental role in host control of TB. We have determined that the sst1 genetic locus which governs necrosis in TB granulomas plays a strong role in coupling macrophage stress signaling with the IFN-I response. We propose that pathogen triggering of the CSP initiates, while an aberrant host response perpetuates, the IFN-I-driven hyperinflammation leading to necrosis. In this proposal we will evaluate TB pathogenesis as a tissue response gone awry rather than the traditional cellular focus on macrophages alone. Our aims are: 1. To dissect mechanisms linking IFN-I responses with integrated stress response (ISR) signaling in susceptible macrophages stimulated with TNFα in vitro, we will identify IFN-I- dependent mechanisms of stress leading to the pre-apoptotic state (PAS) observed in sst1S cells, determine how PAS affects macrophage interactions with M.tb, and whether PAS inhibitors can improve M.tb control and/or macrophage survival. 2. To characterize the IFN-I pathway contribution to macrophage stress signaling and necrosis within lung TB granulomas in vivo, we will identify early biomarkers for necrosis in TB granulomas and determine which IFN-I-dependent pathway plays a dominant role in granuloma necrotization by introducing the IFNAR1 and IRF3 knockout mutations in the B6-sst1S mice. 3. To determine the role of M.tb regulated cyclic dinucleotide (CDN) levels in regulating host macrophage stress signaling, death and intragranulomatous necrosis, we will use a panel of M.tb mutant strains that induce different levels of c-di-AMP and cGAMP to determine how they control macrophage IFN-I and cell death pathways in vitro and granuloma necrosis in vivo. 4. To selectively target mechanisms of granuloma necrosis in vivo using small molecule inhibitors to prevent immunopathology without immune suppression, we will capitalize on our findings to develop novel necrotic granuloma-directed therapies which block the aberrant host responses that drive necrosis in susceptible hosts. We envision that those therapies will correct IFN-I hyperactivity and necrotic inflammation in TB granulomas without suppressing systemic anti-tuberculosis immunity. This approach is especially important for treating multi-drug resistant forms of M.tb, where reducing lung damage, while preserving host immunity, is essential.