Improvement of Liver Transplantation by a Sphingosine Kinase Inhibitor

描述（由申请人提供）：供体器官的严重短缺限制了原位肝移植（LT）的使用，LT是终末期肝病的唯一有效治疗方法。移植后肝移植物的原发性无功能（PNF）通常导致受体死亡或需要再次移植，这进一步加剧了供体肝脏的短缺。不幸的是，PNF的有效治疗方法尚不清楚。肝脏缺血/再灌注（IR）损伤在最初的移植物功能不良和PNF中起重要作用。我们最近令人兴奋的观察表明，鞘氨醇激酶（SK）的抑制显着降低PNF后，肝热IR在体内，这表明鞘脂可能是IR损伤的关键调节器。特别地，SK是在IR损伤中具有核心重要性的炎性细胞的关键调节剂。我们的数据还表明，SK抑制剂阻断由IR诱导的线粒体功能障碍，这是细胞死亡的主要机制。因此，我们假设，SK是一个关键的分子靶点，用于开发新的药物，以预防和/或治疗后的PNF LT。我们最近发现了新的抑制剂SK，比任何其他已知的SK抑制剂更有效，同时具有高特异性和低毒性。我们假设这些SK抑制剂可用于减轻IR诱导的肝损伤，从而改善LT的结局。因此，我们将在本STTR项目的I期进行以下研究：具体目标1。合成足够量的SK抑制剂ABC 294640用于体内研究，表征其在冷藏溶液中的溶解度和稳定性，并测定其在冷藏期间对体内肝脏和外植体的渗透。具体目标2。探讨ABC 294640对大鼠瘦肝移植的保护作用及其机制。具体目标3。探讨ABC 294640在脂肪肝移植中的作用。总之，SK抑制剂代表了一种新的方法，以确定新的抗IR损伤药物。我们将使用大鼠原位LT模型结合最先进的活体多光子显微镜和分子生物学技术，以评估一种先导SK抑制剂作为一种新疗法的临床潜力，该疗法可用于临床，以改善LT的结局。挽救生命的肝移植技术的使用受到可用供体肝脏严重短缺的限制，导致等待接受者名单上的患者死亡。缺血再灌注损伤在许多肝移植物的初始功能不良和随后的失败中起着重要作用。越来越多的信息表明鞘氨醇激酶（SK）活性在缺血后肝毒性中的作用，我们的初步研究表明，这可以通过SK抑制剂显着改善。拟议的研究将确定这种化合物是否有潜力进一步发展为肝移植的保肝药物。

DESCRIPTION (provided by applicant): Severe shortages of donor organs limit the use of orthotopic liver transplantation (LT), the only proven therapy for end-stage liver diseases. Primary non-function (PNF) of liver grafts after transplantation typically results in recipient death or necessitates retransplantation, which further exacerbates the shortage of donor livers. Unfortunately, effective therapies for PNF are not yet known. Liver ischemia/reperfusion (IR) injury plays an essential role in initial poor graft function and PNF. Our recent exciting observations indicate that inhibition of sphingosine kinase (SK) dramatically decreases PNF after hepatic warm IR in vivo, suggesting that sphingolipids may be key regulators of IR injury. In particular, SK is a critical regulator of inflammatory cells that are of central importance in IR injury. Our data also show that the SK inhibitor blocks mitochondrial dysfunction induced by IR, a major mechanism of cell death. Therefore, we hypothesize that SK is a key molecular target for the development of new drugs to prevent and/or treat PNF after LT. We have recently identified novel inhibitors of SK that more potent than any other known SK inhibitor, while being of high specificity and low toxicity. We hypothesize that these SK inhibitors can be used to attenuate IR-induced liver injury and thereby improve the outcome of LT. Therefore, we will conduct the following studies during Phase I of this STTR project: Specific Aim 1. To synthesize sufficient amounts of SK inhibitor ABC294640 for in vivo studies, characterize its solubility and stability in cold storage solution and determine its penetration into liver in vivo and explants during cold storage. Specific Aim 2. To determine the effects of ABC294640 in lean liver transplantation and investigate the mechanisms of protection. Specific Aim 3. To determine the effects of ABC294640 in fatty liver transplantation. Taken together, inhibitors of SK represent a novel approach toward the identification of new anti-IR injury drugs. We will use a rat orthotopic LT model in combination with state-of-the-art intravital multiphoton microscopy and molecular biology techniques to evaluate the clinical potential of a lead SK inhibitor as a new therapy that can be taken to the clinic to improve the outcome of LT. PUBLIC HEALTH RELEVANCE: Use of live-saving liver transplantation techniques is limited by a severe shortage of usable donor livers, resulting in the deaths of patients on recipient waiting lists. Ischemia-reperfusion injury plays an essential role in the initial poor function and consequent failure of many liver grafts. Accumulating information suggests a role for sphingosine kinase (SK) activity in hepatotoxicity following ischemia, and our Preliminary Studies indicate that this can be dramatically improved by an SK inhibitor. The proposed studies will determine if this compound has potential for further development as a hepatoprotective drug for liver transplantation.