PPARgamma and PPARgamma agonists in septic shock

描述(由申请人提供)：在美国，每年有超过75万名患者发生严重脓毒症，是重症监护病房发病率和死亡率的主要原因。细菌产物激活促炎细胞，导致炎症介质的释放，从而诱导脓毒症的全身炎症反应。核因子-kappaB(NF-kappaB)和激活蛋白-1(AP-1)通过与特定的激酶相互作用，在转录水平上调节这些介质的产生。在体外和体内的初步研究中，我们已经获得证据表明，脓毒症的全身炎症反应可能受到核报告蛋白过氧化物酶体增殖物激活受体-γ(PPARGamma)的反向调节。用特异的PPARγ配体15deoxy-delta12，14-PGJ2(15d-PGJ2)或噻唑烷二酮曲格列酮预处理巨噬细胞，可抑制细菌脂多糖(LPS)和热致死金黄色葡萄球菌(HK S)诱导的促炎介质。与这一发现一致，我们发现PPARγ配体可以改善盲肠结扎和穿孔诱导的感染性休克大鼠的存活率，减少血流动力学改变，减少肺、结肠和肝脏中细胞因子的产生和中性粒细胞的浸润。我们的中心假设是核受体PPARGamma是一个关键的抗炎途径，PPARGamma的激活在感染性休克中是有益的。三个相互关联的具体目标将检验这一假设。(1)评价PPAR-γ配体对体内多菌败血症时心血管紊乱和器官衰竭的治疗效果。在盲肠结扎和穿孔的大鼠体内观察15d-PGJ2、噻唑二酮和非噻唑二酮PPARγ配体对脓毒症后遗症的影响。(2)我们将在体内确定PPARγ配体在多菌败血症中作用的分子机制。PPARγ配体对核因子-kappaB和AP-1的核激活以及它们的调节激酶的影响将被检测。(3)研究环戊烯前列腺素和PPAR-γ在脂多糖和金黄色葡萄球菌刺激的巨噬细胞/单核细胞中调节细胞信号转导和炎性介质产生的作用。这种方法将使用PPARGamma的药理拮抗剂和具有PPARGamma显性/阴性结构的遗传操作，以及来自Cre-lox小鼠的PPARGamma缺陷巨噬细胞。体内和体外方法的结合将对激活PPARγ在脓毒症中有益的假说提供强有力的检验。

DESCRIPTION (provided by applicant): Severe sepsis occurs in over 750,000 patients each year in the United States and is the leading cause of morbidity and mortality in critical care units. Activation of pro-inflammatory cells by bacterial products leads to a release of inflammatory mediators that induces the systemic inflammatory response of sepsis. The production of these mediators is regulated at the transcriptional level by enhancer elements nuclear factor kappaB(NF-kappaB) and activator protein-1 (AP-1) through interactions with specific kinases. In preliminary in vitro and in vivo studies we have obtained evidence that the systemic inflammatory response of sepsis may be counter-regulated by the nuclear reporter peroxisome proliferator activated receptor-gamma (PPARgamma). Pretreatment of macrophages with the specific PPARgamma ligands 15deoxy-delta12,14-PGJ2 (15d-PGJ2) or the thiazolidinedione troglitazone inhibits pro-inflammatory mediators induced by bacterial lipopolysaccharide (LPS) and heat killed Staphylococcus aureus (HK S. aureus). Consistent with this finding, we have found that PPARgamma ligands improve survival, reduce hemodynamic alterations, cytokine production and neutrophil infiltration in lung, colon and liver in rats subjected to septic shock induced by cecal ligation and puncture. Our central hypothesis is that the nuclear receptor PPARgamma is a critical anti-inflammatory pathway and that PPARgamma activation is beneficial in septic shock. Three interrelated specific aims will test this hypothesis. (1) We will evaluate the therapeutic efficacy of PPARgamma ligands on cardiovascular derangement and organ failure during polymicrobial sepsis in vivo. The effects of 15d-PGJ2, thiazolidinediones and nonthiazolidinedione PPARgamma ligands on septic sequelae will be examined in vivo in rats subjected to cecal ligation and puncture. (2) We will identify the molecular mechanisms of the actions of PPARgamma ligands in polymicrobial sepsis in vivo. The effect of PPARgamma ligands on nuclear activation of NF-kappaB and AP-1 and their regulatory kinases will be examined. (3) We will determine the role of cyclopentencne prostaglandins and PPARgamma in regulating cell signaling and inflammatory mediator production in macrophages/monocytes challenged in vitro with LPS and HK S. aureus. This approach will employ pharmacologic antagonists of PPARgamma and genetic manipulations with PPARgamma dominant/negative constructs and PPARgamma deficient macrophages from Cre-lox mice. The combination of in vivo and in vitro approaches will provide a strong test of the hypothesis that activation of PPARgamma is beneficial in sepsis.