Cardiac Inflammation in Resuscitated Hemorrhagic Shock

描述（由申请人提供）：最近的研究表明，复苏的失血性休克导致一系列炎症介质（包括肿瘤坏死因子（TNF）、白细胞介素-1 β（IL-1b）、白细胞介素-6（IL-6）和一氧化氮（NO））的表达不适当或“功能失调”增加，这反过来又会引起心脏中的许多有害作用，最明显的是LV功能障碍。炎症介质是“先天免疫系统”的主要效应蛋白，先天免疫系统是一种遗传学上保守的早期预警系统，使宿主能够快速辨别环境中的“危险信号”（例如ROI）。该实验室和其他实验室的研究已经确定了心脏中存在一个称为Toll样受体（TLR）的先天免疫受体家族。重要的是，这些研究表明，Toll样受体介导的信号传导激活心脏中的促炎介质，以响应各种不同形式的环境应激，包括氧化应激。我们在TLR-2介导的信号传导（TLR-2D）缺陷的小鼠中的初步研究表明TLR-2小鼠具有较少的再灌注诱导的炎症介质表达，并且对缺血-再灌注损伤对LV功能的有害影响具有抗性。根据上述意见，本提案的直接具体目标是检验以下假设：（1）通过Toll样受体2（TLR-2）的信号传导通过MyD 88/TIRAP依赖性途径放大心脏中炎症介质的再灌注诱导的表达，（2）TLR-2介导的炎症介质的扩增加重了失血性休克复苏后伴随的LV功能障碍。这些假设将使用低流量缺血再灌注（LF-I/R）离体和复苏的出血性休克（R-H/S）体内的相互互补的小鼠模型系统进行测试。有四个目标。在具体目标1中，我们将测试以下假设：通过TLR-2的信号传导通过MyD 88/TIRAP依赖性信号传导途径放大LFI/ R损伤后心脏中炎症介质的表达。具体目标2将检验TLR-2介导的信号传导通过增加炎症介质的表达而夸大低流量缺血/再灌注LF-I/R后发生的左心室（LV）功能障碍的假设。在具体目标3中，我们将检验以下假设：通过TLR-2的信号传导通过MyD 88/TIRAP依赖性信号传导途径放大复苏后出血性休克（R-HS）心脏中炎症介质的表达。具体目标4将检验TLR-2介导的信号传导通过增加炎症介质的表达而夸大R-HS后发生的左心室（LV）功能障碍的假设。总的来说，特异性目的1-4应该提供关于激活机制的明确的新信息，以及先天性免疫系统在复苏的失血性休克中的作用。

DESCRIPTION (provided by applicant): Recent studies suggest that resuscitated hemorrhagic shock leads to an inappropriate or "dysfunctional" increase in the expression of a portfolio of inflammatory mediators, including tumor necrosis factor (TNF), interleukin-1beta (IL-1b), interleukin-6 (IL-6) and nitric oxide (NO), which can in turn provoke a number of deleterious effects in the heart, most notably LV dysfunction. Inflammatory mediators are principal effector proteins of the "innate immune system," a phylogenetically conserved early warning system that enables the host to rapidly discriminate "danger signals" (e.g. ROIs) in the environment. Studies from this and other laboratories have identified the presence of a family of innate immune receptors in the heart termed Toll-like receptors (TLRs). Importantly, these studies have shown that Toll-like receptor mediated signaling activates proinfiammatory mediators in the heart in response to a variety of different forms of environmental stress, including oxidative stress. Our preliminary studies in mice that are deficient in TLR-2 mediated signaling (TLR-2D) show that TLR-2 mice have less reperfusion induced expression of inflammatory mediators and are resistant to the deleterious effects of ischemia-reperfusion injury on LV function. Based upon the foregoing observations the immediate specific objective of this proposal will be to test the following hypotheses: (1) Signaling through Toll-like receptor 2 (TLR-2) amplifies reperfusion-induced expression of inflammatory mediators in the heart through a MyD88/TIRAP dependent pathway, and (2) TLR-2 mediated amplification of inflammatory mediators exaggerates the LV dysfunction that supervenes following resuscitated hemorrhagic shock. These hypotheses will be tested using mutually complementary murine model systems of low-flow ischemia reperfusion (LF-I/R) ex vivo and resuscitated hemorrhagic shock (R-H/S) in vivo. Four Aims are envisioned. In Specific Aim 1 we will test the hypothesis that signaling through TLR-2 amplifies the expression of inflammatory mediators in the heart following LFI/ R injury through a MyD88/TIRAP dependent signaling pathway. Specific Aim 2 will test the hypothesis that TLR-2 mediated signaling exaggerates the left ventricular (LV) dysfunction that occurs following low-flow ischemia/reperfusion LF-I/R through increased expression of inflammatory mediators. In Specific Aim 3, we will test the hypothesis that signaling through TLR-2 amplifies the expression of inflammatory mediators in the heart following resuscitated hemorrhagic shock (R-HS) through a MyD88/TIRAP dependent signaling pathway. Specific Aim 4 will test the hypothesis that TLR-2 mediated signaling exaggerates the left ventricular (LV) dysfunction that occurs following R-HS through increased expression of inflammatory mediators. Taken together, Specific Aims 1-4 should provide definitive new information regarding the mechanisms of activation, as well as the role of the innate immune system in resuscitated hemorrhagic shock.