Cellular mechanism of immune dysfunction following burn injury

描述（由申请人提供）：严重烧伤后死亡的主要原因是脓毒症和继发于深刻的先天和适应性免疫功能障碍的多系统器官衰竭，尽管这些反应的控制机制尚不清楚。免疫活性的主要决定因素是先天toll样受体（TLR）和核苷酸结合寡聚化结构域（NOD）样受体（NLR）家族。它们由许多免疫细胞表达，其主要功能是感知导致细胞因子释放或细胞死亡的微生物分子。我们的总体假设是，烧伤后先天免疫系统和适应性免疫系统的损伤是由TLR和NLR信号直接介导的。本实验旨在在烧伤后的两个免疫致病阶段验证这一假设，并研究先天受体阻断作为烧伤患者临床相关问题的可能免疫治疗方法。首先，为了确定损伤后TLR和NLR信号控制先天免疫系统的机制：我们将使用烧伤动物模型来确定MF和DC的表型和功能（细胞因子和细胞死亡）变化。我们将在烧伤早期和晚期将TLR和NLR的表达与其功能变化联系起来。然后，我们将使用TLR和NLR缺陷小鼠来验证改变的烧伤介导的先天免疫反应是通过先天受体信号传导介导的。其次，为了确定先天信号控制烧伤后适应性免疫反应的机制：我们将研究烧伤对TLR和NLR在CD4+和CD8+ T细胞及相关T细胞亚群上的表达和激活的影响。我们将把TLR和NLR表达的变化与T细胞引发适应性免疫反应的能力联系起来。为了确定直接（先天受体在T细胞上的表达）和间接（MF或DC上的表达）先天受体在介导烧伤适应性反应中的相对重要性，我们将先天信号受体缺乏的T细胞或MF和DC转移到烧伤或假受体中，并测试T细胞的免疫功能和存活。第三，为了证明先天受体对体内烧伤损伤的功能失调免疫反应至关重要：我们将使用TLR和NLR先天信号缺失的小鼠来研究先天受体在介导皮肤同种异体移植排斥和防止烧伤后有效免疫耐受建立中的作用。我们将利用TLR和NLR信号缺失的小鼠，研究先天信号通路在烧伤后早期和晚期介导铜绿假单胞菌易感性中的重要性。公共卫生相关性：严重烧伤后死亡的主要原因是不受控制的感染和器官衰竭。这是由于患者的免疫系统存在严重问题。我们建议确定这些免疫问题背后的细胞和分子机制。

DESCRIPTION (provided by applicant): The leading causes of death following serious burn injury are sepsis and multiple system organ failure secondary to profound innate and adaptive immune dysfunction, though the controlling mechanism for the response is unknown. Major determinants of immune activity are the innate Toll-like receptor (TLR) and nucleotide binding oligomerization domain (NOD)-like receptor (NLR) families. These are expressed by many immune cells and their primary function is to sense microbial molecules leading to cytokine release or cell death. Our overall hypothesis is that impairment of both the innate and adaptive immune systems after burn injury is mediated directly by TLR and NLR signaling. The proposed experiments are designed to test this hypothesis during both immunopathogenic phases after burn injury and investigate innate receptor-blockade as a possible immunotherapeutic approach for clinically relevant issues facing burn patients. First, to determine the mechanism by which TLR and NLR signaling controls the innate immune system after injury: We will determine phenotypic and functional (cytokine and cell death) changes of MF and DC using an animal model of burn injury. We will correlate TLR and NLR expression with changes in their function during early and late after burn injury. We will then use TLR and NLR deficient mice to validate that the altered burn injury-mediated innate immune response is mediated through innate-receptor signaling. Second, to determine the mechanism by which innate signaling controls the adaptive immune response after burn injury: We will examine the effect of burn injury on the expression and activation of TLR and NLR on CD4+ and CD8+ T cells and relevant T cell subsets. We will correlate changes in TLR and NLR expression with the ability of T cells to elicit an adaptive immune response. To determine the relative importance of both direct (expression of innate receptors on T cells) and indirect (expression on MF or DC) innate receptor expression in mediating the adaptive response to burn injury, we will transfer T cells or MF and DC, deficient in innate signaling receptors, into burn or sham recipients and test T cell immune function and survival. Third, to demonstrate that innate receptors are critical for the dysfunctional immunologic response to burn injury in vivo: We will use mice deficient in TLR and NLR innate signaling to examine the role of innate receptors in mediating skin allograft rejection and preventing establishment of effective immune tolerance after burn. We will examine the importance of innate signaling pathways in mediating Pseudomonas aeruginosa susceptibility early and late after burn injury using mice deficient in TLR and NLR signaling. PUBLIC HEALTH RELEVANCE: The leading causes of death following serious burn injury are uncontrolled infection and organ failure. These are due to profound problems with the patient's immune system. We propose to determine the cellular and molecular mechanisms underlying these immune problems.