Inhibitory Pathways Underlying Viral Persistence In Vivo

摘要 持续的病毒感染涉及病原体和免疫系统之间的长期平衡。为 对此，免疫细胞必须适应，以控制病原体，同时将免疫病理学降至最低。这 免疫适应最好的例证是“耗尽的”CD8T细胞(TeX)，它最初是在一个模型中描述的 小鼠感染持续性淋巴细胞性脉络膜脑膜炎病毒(LCMV)克隆13株(Cl13)。在……里面 同样的模型，TeX也首次被证明逐渐丧失效应功能，表达高水平的 抑制性受体，如程序死亡-1(PD-1)和在转录和表观遗传上与 其他CD8 T细胞谱系。Tex也被证明是一个异质性群体，具有Tex效应样细胞 (Teff样细胞)和干细胞样细胞(Tex-Stem)在感染后几天内出现竞争分化路径。画眉草- LIKE是短暂的，有助于遏制早期病毒传播，但也会导致免疫病理。相比之下，德克萨斯州- 干细胞自我更新和维持TeX池，对于长期免疫和PD-1的成功至关重要- 免疫疗法。因此，了解规范TeX开发和维护的因素可能会提供 关于我们如何利用这些TeX亚集来治疗持续的病毒感染的独特见解。 白色脂肪组织(Wat)和棕色脂肪组织(BAT)都是全身的中枢调节因子 新陈代谢。Wat储存的能量可以通过脂肪分解和提供游离脂肪酸(FFA)来释放 在需要的时候。相比之下，蝙蝠是一种新陈代谢要求很高的组织，它消耗大量的 维持核心体温的葡萄糖。通过非靶向代谢组学，我们揭示了一种惊人的营养 在LCMV Cl13感染后的前10天内转移。简而言之，我们检测到了显著的系统性增长 FFA和葡萄糖的减少，这与Wat脂肪分解和BAT产热的变化相一致。 值得注意的是，Wat脂解受到遗传抑制的小鼠表现出FFA减少，Tex-Stem减少和 增强效应分子颗粒酶B(GrzB)的表达。另一方面，蝙蝠的缺席 产热导致GrzB和CD8-T细胞介导的死亡增加，而刺激蝙蝠产热 效应者CD8T细胞减少，病毒控制延迟。这些结果首次证明了病毒-- 在感染后，特定的CD8T细胞可以被遥远的、非免疫的、代谢相关的组织调节。 我们的总体目标是利用这些令人兴奋的初步数据，并研究Wat (目标1)和BAT(目标2)通过提供和调节持续感染期间的CD8 T细胞反应 限制可用营养素(分别为游离脂肪酸和葡萄糖)，进而影响CD8-T细胞代谢 和分化，最终影响感染结果。这项工作将建立第一个基础 代谢相关的非免疫组织远距离调节抗病毒CD8T细胞的原理， 在研究抗病毒药物时打开了一种范式转换的视角来考虑宿主的生物能量学 免疫力和针对患者的全球新陈代谢来缓解传染病的可能性。

ABSTRACT Persistent viral infections involve long-term equilibrium between the pathogen and the immune system. For this, immune cells must adapt in order to keep the pathogen in check while minimizing immunopathology. This immune adaptation is best exemplified by “exhausted” CD8 T cells (TEx), which were first described in a model of murine infection with the persistent lymphocytic choriomeningitis virus (LCMV) isolate Clone 13 (Cl13). In the same model, TEx were also first shown to progressively lose effector functions, express high levels of inhibitory receptors such as program-death-1 (PD-1) and be transcriptionally and epigenetically distinct from other CD8 T cell lineages. TEx were also shown to be a heterogeneous population, with TEx effector-like cells (TEff-like) and stem-like cells (TEx-Stem) emerging as competing differentiation paths within days after infection. TEff- like are short-lived and help to contain early viral spread but can also cause immunopathology. In contrast, TEx- Stem cells self-renew and maintain the TEx pool, being critical for long-term immunity and the success of PD-1- immunotherapy. Thus, understanding the factors that regulate TEx development and maintenance may offer unique insights into how we might exploit these TEx subsets to treat sustained viral infections. White adipose tissue (WAT) and brown adipose tissue (BAT) are both central regulators of whole-body metabolism. WAT stores energy which can be released via lipolysis and provision of free fatty acids (FFA) in times of need. In contrast, BAT is a highly metabolically demanding tissue that consumes great quantities of glucose to maintain core body temperature. Via untargeted metabolomics, we revealed a striking nutritional shift within the first ten days after LCMV Cl13 infection. In brief, we detected a profound systemic increase in FFA and a reduction in glucose, which coincided with WAT lipolysis and changes in BAT thermogenesis. Remarkably, mice with genetic inhibition of WAT lipolysis exhibited reduced FFA, decreased TEx-Stem and enhanced expression of the effector molecule granzyme B (GrzB). On the other hand, absence of BAT thermogenesis led to enhanced GrzB and CD8-T-cell-mediated death, while stimulation of BAT thermogenesis reduced effector CD8 T cells and delayed viral control. These results provide the first evidence that virus- specific CD8 T cells can be regulated by distant, non-immune, metabolically relevant tissues after an infection. Our overall goal is to leverage these exciting preliminary data and investigate the unique hypothesis that WAT (Aim 1) & BAT (Aim 2) regulate CD8 T cell responses during persistent infection through the provision and restriction of available nutrients (FFA and glucose, respectively), which in turn influence CD8-T-cell metabolism and differentiation, ultimately affecting the infection outcome. This work will establish the first foundational principles for a long-distance regulation of antiviral CD8 T cells by metabolically-relevant non-immune tissues, opening both a paradigm-shifting perspective to consider the host's bioenergetics when studying antiviral immunity and the possibility of targeting a patient's global metabolism to alleviate infectious diseases.