Targeting Trained Immunity in Trauma-Induced Immune Dysregulation

项目总结/摘要 烧伤、爆炸或大手术造成的创伤性损伤使免疫系统功能失调， 受伤的人危及生命的机会性感染或持续的危重病。靶向免疫疗法 用于创伤性损伤以恢复免疫系统功能和体内平衡的方法尚未开发， 迫切需要。人类免疫表型的多样性为进化靶向提供了坚实的理由 保守的先天性免疫调节网络对于治疗来说不那么异质。因此， 通过一种被称为“训练免疫”的过程对先天免疫细胞进行重新编程， 治疗，以减少创伤引起的并发症的发病率和死亡率。训练有素的免疫力可以 通过表观遗传学修饰免疫调节基因的可及性， 造血干细胞（HSC），然后通过分化传递到先天效应细胞，使它们 更好地应对感染我们已经开发了Toll样受体9（TLR 9）激动剂-非甲基化 CpG-DNA序列，天然存在于细菌DNA和真核细胞线粒体中-如 促进放射损伤后免疫系统恢复免疫医学对策 受伤我们最近发现，间充质基质细胞（MSC），这是关键的细胞居民， 表达高水平TLR 9骨髓造血干细胞（HSC）龛对CpG-DNA有强烈反应 刺激，并介导对感染的紧急粒细胞生成反应。这一发现 促使我们考虑训练的免疫力作为一个中心机制，有助于免疫保护， 在我们的烧伤创伤和感染模型中的系统性CpG-DNA治疗。在这里，我们提出一个假设， TLR 9激动剂治疗介导保护性免疫并通过训练的免疫恢复免疫稳态 涉及骨髓间充质干细胞和造血干细胞的机制。为了验证这一假设，我们提出了以下具体的 目的：1）探讨CpG-DNA治疗创伤后造血和外周免疫功能的变化 2）鉴定损伤后骨髓间充质干细胞和造血干细胞的转录和表观遗传变化， 和用CpG-DNA处理的未损伤小鼠，和3）产生和使用嵌合小鼠模型来描绘 损伤和CpG-DNA诱导的HSC转移的训练免疫表型。我们预计， 从这项研究计划将提供临床前机制的见解，对翻译CpG-DNA作为一个 创伤诱导免疫失调的免疫治疗策略。

PROJECT SUMMARY/ABSTRACT Traumatic injuries from burns, blasts, or major surgery dysregulates immune system function predisposing the injured people to life-threatening opportunistic infections or persistent critical illness. Targeted immunotherapies for traumatic injuries to restore immune system function and homeostasis have not yet been developed and are urgently needed. The immunophenotypic diversity in humans provides a solid justification to target evolutionarily conserved innate immunoregulatory networks that are less heterogenous for treatment. As such, the reprogramming of innate immune cells by a process called “trained immunity” is a promising concept for targeting therapeutics to reduce the morbidity and mortality from trauma-induced complications. Trained immunity can occur in short-lived innate immune cells by epigenetically modifying accessibility to immune regulatory genes in hematopoietic stem cells (HSC), which are then passed on by differentiation to innate effector cells, leaving them better poised to respond to infection. We have developed Toll-like receptor 9 (TLR9) agonists – unmethylated CpG-DNA sequences, which are naturally found in bacterial DNA and eukaryotic cell mitochondria - as immunotherapeutic medical countermeasures to promote immune system recovery after radiation and traumatic injuries. We recently discovered that mesenchymal stromal cells (MSCs), which are critical cellular residents in the bone marrow hematopoietic stem cell (HSC) niche, express high TLR9 levels, strongly react to CpG-DNA stimulation, and mediate emergency granulopoiesis responses to infection in neutropenic mice. This discovery prompted us to consider trained immunity as a central mechanism contributing to the immune protection from systemic CpG-DNA treatment in our burn trauma and infection model. Here, we address the hypothesis that TLR9 agonist therapy mediates protective immunity and restores immune homeostasis by trained immunity mechanisms involving bone marrow MSCs and HSCs. To test this hypothesis, we propose the following specific aims: 1) To delineate hematopoietic and peripheral immune consequences of trauma with CpG-DNA therapeutic intervention, 2) To identify transcriptional and epigenetic changes in bone marrow MSCs and HSCs from injured and uninjured mice treated with CpG-DNA, and 3) To generate and use chimeric mouse models to delineate injury and CpG-DNA induced trained immunity phenotypes transferred by HSCs. We anticipate that the results from this research program will provide pre-clinical mechanistic insights towards translating CpG-DNA as an immunotherapeutic strategy for trauma-induced immune dysregulation.