Enhancing Resistance to Infection after Burn Injury with TLR Agonists

摘要 感染是严重烧伤患者存活后死亡和延长住院时间的主要原因 受伤的急性期。皮肤屏障丧失、先天免疫力受损和抗生素泛滥 耐药细菌增加了烧伤患者对严重感染的易感性，导致对 免疫调节策略旨在启动这些患者的宿主反应。用TLR4引爆-- 已有研究表明，NIST可以增强中性粒细胞的抗微生物反应，并增强对Infec-2的抵抗力。 对严重烧伤小鼠的治疗作用。然而，经典的依赖于MyD88和TRIF的TLR sig- 纳林在调节这一保护方面的级联作用，还没有完全被理解。初步研究支持初选 MyD88信号在介导抗菌反应中的作用，可能是通过增加白细胞 通过诱导PI3K信号通路代谢，但涉及的细胞和分子机制 都不清楚。该项目的长期目标是更好地理解MyD88和TRIF的不同作用- TLR配体在免疫调节过程中的依赖信号。总体目标是找出潜在的 免疫调节策略作为防止烧伤患者感染的一种手段。中环 假设MyD88依赖的信号通路在促进TLR激动剂诱导的增强中起关键作用。 MyD88特异性TLR激动剂将在免疫治疗中发挥高效作用。 证明烧伤后中性粒细胞介导的抗感染作用。这一假设将通过以下方式检验 三个具体目标：目标1：确定选择性激活TLR激动剂的治疗是否 MyD88和TRIF信号通路可以改善烧伤小鼠对不同病原体的宿主反应。 这一目标将通过给烧伤小鼠注射MyD88特异性(CpG)或Trif特异性(PolyI：C)激动剂来实现 以及评估金黄色葡萄球菌、白色念珠菌和铜绿假单胞菌攻击后的结果和感染清除。 莎拉。目的2：明确MyD88和TRIF特异性激动剂治疗慢性粒细胞白血病的细胞机制。 影响烧伤后感染的先天免疫反应。烧伤的小鼠将在之前被准备好特定的途径- 如目标1所示，将分析中性粒细胞的扩张、运输、激活和抗菌功能。 目的3：明确TLR激动剂增强烧伤后抗菌免疫的分子机制 受伤。为此，TLR激动剂对PI3K/Akt/mTor/Hif-1α信号通路的激活及其作用 这种通过增强白细胞代谢来介导抗菌反应的信号通路将是 检查过了。本项目中提出的研究代表了一种全新的预防传染病的方法-- 感染和败血症，这是翻译和高度创新的。这些研究具有重要意义，因为它们还将 通过促进我们对细胞和分子机制的理解来填补重要的知识空白 哪种基于TLR的免疫调节剂可提高宿主对危及生命的急性感染的抵抗力。

ABSTRACT Infection is the leading cause of death and prolonged hospitalization in severely burned patients that survive the acute phase of injury. Loss of the skin barrier, impaired innate immunity and the prevalence of antibiotic resistant bacteria increase the susceptibility of burn patients to serious infection, leading to a great need for immunomodulation strategies aimed at priming the host response in these patients. Priming with TLR4 ago- nists have been shown to augment neutrophil antimicrobial responses and enhance resistance against infec- tion after severe burn injury in mice. However, the role of the classical MyD88- and TRIF-dependent TLR sig- naling cascades in mediating this protection, are not fully understood. Preliminary studies support a primary role for MyD88-signaling in mediating antimicrobial responses, potentially through augmentation of leukocyte metabolism via induction of the PI3K signaling pathway, but the cellular and molecular mechanisms involved are unclear. The long-term goal of this project is to better understand the distinct roles of MyD88- and TRIF- dependent signaling during immunomodulation with TLR ligands. The overall objective is to identify potential immunomodulatory strategies as a means of offering protection against infection in burn patients. The central hypothesis is that Myd88-dependent signaling is crucial in facilitating TLR agonist-induced augmenta- tion of antimicrobial responses, and that MyD88-specific TLR agonists will be highly effective in im- proving neutrophil-mediated resistance to infection after burn injury. This hypothesis will be tested by three specific aims: Aim 1: To determine whether treatment with TLR agonists that selectively activate the MyD88- and TRIF-signaling pathways can improve the host response to diverse pathogens in burned mice. This aim will be achieved by priming burned mice with MyD88-specific (CpG) or Trif-specific (PolyI:C) agonists and evaluating outcome and clearance of infection after challenge with S. aureus, C. albicans and P. aerugino- sa. Aim 2: To define the cellular mechanisms by which treatment with MyD88- and TRIF-specific agonists af- fect innate immune responses to infection after burn. Burned mice will be primed with pathway specific ago- nists as in Aim 1, and neutrophil expansion, trafficking, activation, and antimicrobial functions will be analyzed. Aim 3: To define the molecular mechanisms by which TLR agonists augment antimicrobial immunity after burn injury. In this aim, activation of the PI3K/Akt/mTOR/Hif-1α signaling pathway by TLR agonists and the role of this signaling pathway in mediating antimicrobial responses via augmentation of leukocyte metabolism will be examined. The studies proposed in this project represent an entirely novel approach to the prevention of infec- tion and sepsis which is translational and highly innovative. These studies are significant in that they will also fill important gaps in knowledge by advancing our understanding of the cellular and molecular mechanisms by which TLR-based immunomodulators improve host resistance to acute life-threatening infections.