Cardiac Inflammation in Resuscitated Hemorrhagic Shock

描述(由申请人提供)：最近的研究表明，复苏的失血性休克会导致一系列炎症介质，包括肿瘤坏死因子(TNF)、白介素1b(IL-1b)、白介素6(IL-6)和一氧化氮(NO)的不适当或“功能失调”的表达增加，这反过来又会引起心脏的一些有害影响，最明显的是左心功能不全。炎症介质是“先天免疫系统”的主要效应蛋白，“先天免疫系统”是一种系统发育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)。来自该实验室和其他实验室的研究已经确定心脏中存在一种被称为Toll样受体(TLRs)的先天免疫受体家族。重要的是，这些研究表明，Toll样受体介导的信号可激活心脏中的前炎性介质，以应对包括氧化应激在内的各种不同形式的环境应激。我们对TLR-2介导的信号转导(TLR-2D)缺陷小鼠的初步研究表明，TLR-2小鼠再灌注诱导的炎症介质表达较少，并能抵抗缺血再灌注损伤对左心功能的有害影响。基于上述观察，该方案的直接目标是检验以下假设：(1)通过Toll样受体2(TLR-2)的信号通过MyD88/TIRAP依赖的途径放大再灌流诱导的心脏炎症介质的表达，以及(2)TLR-2介导的炎症介质的放大夸大了复苏失血性休克后引起的左心功能障碍。这些假说将用相互补充的小鼠低流量缺血再灌注(LF-I/R)体外模型和复苏失血性休克(R-H/S)体内模型系统进行验证。设想了四个目标。在特定的目标1中，我们将检验这样的假设，即通过TLR-2信号通过MyD88/TIRAP依赖的信号通路放大LFI/R损伤后心脏炎症介质的表达。特定目的2将验证TLR-2介导的信号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，我们将验证这样的假设，即通过TLR-2信号通过MyD88/TIRAP依赖的信号通路放大复苏失血性休克(R-HS)后心脏炎症介质的表达。具体目标4将验证这样的假设，即TLR-2介导的信号通过增加炎症介质的表达而夸大了R-HS后发生的左心室(LV)功能障碍。总而言之，特定的AIMS 1-4应该提供关于激活机制以及先天免疫系统在复苏失血性休克中的作用的明确的新信息。

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.