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败血症和继发于严重先天性和适应性免疫功能障碍的多系统器官衰竭，尽管该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性Toll样受体（TLR）和核苷酸结合寡聚化结构域（NOD）样受体（NLR）家族。这些由许多免疫细胞表达，其主要功能是感知微生物分子，导致细胞因子释放或细胞死亡。我们的总体假设是，烧伤后先天性和适应性免疫系统的损害是由TLR和NLR信号直接介导的。所提出的实验旨在测试这一假设在烧伤后的两个免疫病理阶段，并调查先天受体阻断作为一种可能的免疫治疗方法，烧伤患者面临的临床相关问题。首先，为了确定TLR和NLR信号传导在损伤后控制先天免疫系统的机制：我们将使用烧伤动物模型确定MF和DC的表型和功能（细胞因子和细胞死亡）变化。我们将TLR和NLR的表达与烧伤后早期和晚期的功能变化相关联。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应答是通过先天受体信号传导介导的。其次，确定先天信号传导控制烧伤后适应性免疫反应的机制：我们将研究烧伤对CD 4+和CD 8 + T细胞及相关T细胞亚群上TLR和NLR表达和激活的影响。我们将TLR和NLR表达的变化与T细胞引发适应性免疫应答的能力相关联。为了确定直接（T细胞上先天受体的表达）和间接（MF或DC上的表达）先天受体表达在介导对烧伤的适应性反应中的相对重要性，我们将先天信号传导受体缺陷的T细胞或MF和DC转移到烧伤或假受体中，并测试T细胞免疫功能和存活。第三，为了证明先天性受体在体内对烧伤损伤的功能失调的免疫反应中是至关重要的：我们将使用TLR和NLR先天性信号传导缺陷的小鼠来研究先天性受体在介导皮肤同种异体移植排斥反应和防止烧伤后建立有效的免疫耐受中的作用。我们将使用TLR和NLR信号缺陷的小鼠研究先天信号通路在介导烧伤后早期和晚期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。这是由于患者免疫系统的严重问题。我们建议确定这些免疫问题的细胞和分子机制。

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.