Injury-Specific Activation of the Immune System

描述（由申请人提供）：严重损伤后免疫系统的炎症和抗炎行为决定了危重患者的临床轨迹。例如，显性抗炎表型将抑制正常的抗微生物免疫并使宿主易于机会性感染。另一方面，如果受伤患者发生感染性并发症，则炎症的增强可促进全身性炎性休克。我们已经报道了一种称为调节性T细胞（Tcells）的CD 4 T细胞亚群被损伤激活，并有效抑制T细胞介导的免疫功能和损伤诱导的炎症。因此，我们认为，TGFAP作为一种损伤反应性细胞亚群，具有控制先天性和适应性免疫功能的能力。本项目中的实验将验证这一假设，并将揭示负责损伤快速激活TcR的细胞和分子途径。提出了以下具体目标：1。以确定T细胞是否通过抗原受体依赖性或非依赖性机制被损伤激活。CD 4 T细胞通过T细胞受体（TCR）与抗原呈递细胞上的细胞表面MHC II类（MHCII）分子呈递的抗原结合而特异性活化。该目的的实验将使用MHCII基因缺陷（MHCII-/-）小鼠、FoxP 3-GFP基因敲入小鼠和过继转移方法来解决MHCII对Treg活化的依赖性。先天性（MyD 88和TRIF）和T细胞共刺激途径（CD 40 L、CD 28和CTLA-4）也将作为潜在的MHCII非依赖性途径进行测试，以用于TclF的损伤特异性激活。2.通过TdR表征损伤特异性激活和信号传导。烧伤早期激活的TGFAP表明，TGFAP反应迅速，特异性损伤。在这个目标中，我们建议确定和研究TCR依赖性和TCR非依赖性的信号通路，在烧伤小鼠TCRs激活。该目的的实验将使用磷酸化流式细胞术来测量Tcl 3的MHCII-、TLR-、CD 28-、CD 40 L-或CTLA 4-依赖性活化。3.目的：通过Tendon来定义损伤特异性回忆反应的特异性和性质。最近的发现表明，TdR对烧伤表现出回忆记忆样反应，这支持了TdR可能对损伤有特异性反应的观点。这一目标的研究将进一步调查这一基本发现，并将利用这一观察结果来促进我们对损伤特异性免疫反应的理解。该项目的临床意义在于，这些信息可用于开发控制严重创伤和手术患者免疫系统并发症的创新方法。 公共卫生相关性：严重损伤后免疫系统的行为决定了危重患者的临床病程。我们已经报道了一个独特的CD 4 T细胞亚群，称为调节性T细胞（T细胞），该项目的重点将是确定负责损伤激活Treg的起始细胞和分子途径，为开发控制免疫系统并发症的创新方法提供基础信息。严重创伤和外科病人。

DESCRIPTION (provided by applicant): The inflammatory and counter-inflammatory behavior of the immune system following severe injury governs the clinical trajectory of critically-injured patients. For example, a dominant counter- inflammatory phenotype will suppress normal anti-microbial immunity and predispose the host to opportunistic infections. On the other hand, augmentation of inflammation can promote systemic inflammatory shock if infectious complications occur in injured patients. We have reported that a distinct subset of CD4 T cells called regulatory T cells (Tregs) are activated by injury and act to potently suppress both T cell mediated immune function and injury-induced inflammation. Thus, we suggest that Tregs act as an injury-reactive cell subset with the capacity to control both innate and adaptive immune function. The experiments in this project will test this hypothesis and will uncover the cellular and molecular pathways responsible for the rapid activation of Tregs by injury. The following specific aims are proposed: 1. to determine if Tregs are activated by injury by antigen receptor dependent or independent mechanisms. CD4 T cells are specifically activated by T cell receptor (TCR) binding to antigens presented by cell-surface MHC class II (MHCII) molecules on antigen presenting cells. The experiments in this aim will address the MHCII-dependence on Treg activation using MHCII gene deficient (MHCII-/-) mice, FoxP3-GFP gene knock-in mice, and adoptive transfer approaches. Innate (MyD88 and TRIF) and T cell costimulatory pathways (CD40L, CD28, and CTLA-4) will also be tested as potential MHCII independent pathways for the injury-specific activation of Tregs. 2. To characterize injury-specific activation and signaling by Tregs. The early activation of Tregs by burn injury suggests that Tregs respond rapidly and specifically to injury. In this aim, we propose to identify and study TCR-dependent and TCR-independent signaling pathways that are activated in Tregs by burn injury in mice. The experiments in this aim will use phospho-flow cytometry to measure MHCII-, TLR-, CD28-, CD40L-, or CTLA4-dependent activation of Tregs. 3. To define the specificity and nature of injury-specific recall responses by Tregs. The recent discovery that Tregs display a recall memory-like response to burn injury supports the idea that Tregs may respond specifically to injury. Studies in this aim will further investigate this basic finding and will use this observation to advance our understanding of injury-specific immune responses. The clinical significance of this project is that this information could be used to develop innovative approaches for controlling the immune system complications that occur in critically-injured trauma and surgical patients. PUBLIC HEALTH RELEVANCE: The behavior of the immune system following severe injury governs the clinical course of critically-injured patients. We have reported that a distinct subset of CD4 T cells called regulatory T cells (Tregs) are activated by injury and that Tregs can potently suppress immune system responses following injury in mice and man. The focus of this project will be to identify the initiating cellular and molecular pathways responsible for Treg activation by injury to generate basic information for developing innovative approaches for controlling immune system complications in critically-injured trauma and surgical patients.