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，这是唯一被证实的治疗终末期肝病的方法。肝移植后的原发无功能(PNF)通常会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，目前还不知道治疗PNF的有效方法。肝脏缺血再灌注(IR)损伤在早期移植物功能不良和PNF中起重要作用。我们最近令人兴奋的观察表明，抑制鞘氨醇激酶(SK)显著降低了活体肝脏热缺血再灌注后的PNF，提示鞘氨醇可能是IR损伤的关键调节因素。特别是，SK是炎症细胞的关键调节因子，而炎症细胞在IR损伤中起着核心作用。我们的数据还表明，SK抑制剂可以阻断IR诱导的线粒体功能障碍，IR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，用于开发预防和/或治疗肝移植后PNF的新药。我们最近发现了新的SK抑制剂，它比任何其他已知的SK抑制剂更有效，同时具有高特异性和低毒性。我们推测，这些SK抑制剂可用于减轻IR诱导的肝损伤，从而改善肝移植的结局。因此，我们将在本项目的第一阶段进行以下研究：具体目标1.合成足够数量的SK抑制剂ABC294640，用于体内研究，表征其在冷藏溶液中的溶解性和稳定性，并测定其在体内的肝脏和冷藏期间的外植体渗透。具体目的2.检测ABC294640在瘦肝移植中的作用，并探讨其保护机制。具体目的3.确定ABC294640在脂肪肝移植中的作用。综上所述，SK的抑制剂代表了一种识别新的抗IR损伤药物的新途径。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来评估SK铅抑制剂作为一种新的治疗方法的临床潜力，该疗法可以应用于临床，以改善LT的结果。公共卫生相关性：挽救生命的肝移植技术的使用受到可用供肝严重短缺的限制，导致等待受者名单上的患者死亡。缺血再灌注损伤在许多肝移植最初的功能不良和随后的失败中起重要作用。越来越多的信息表明，鞘氨酸激酶(SK)活性在缺血后肝毒性中起作用，我们的初步研究表明，SK抑制剂可以显著改善这一作用。拟议的研究将确定该化合物是否有潜力进一步开发为肝移植的肝脏保护药物。

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.