Lipid Mediators in Pancreatic Islet Dysfunction

描述（由申请人提供）：自身免疫介导的胰腺β细胞损伤是胰岛移植受者发生1型糖尿病（T1DM）及其复发的关键。促炎细胞因子和脂质介质是导致β细胞损伤的重要因素。我们重点研究了12-脂氧合酶（12LO）在导致免疫介导的β细胞破坏中的花生四烯酸代谢的作用。12LO可被促炎细胞因子激活和诱导。lo代谢物可启动细胞内信号级联反应，导致β细胞功能障碍和死亡。在本提案中，我们将验证12LO途径在自身免疫介导的炎症反应中起关键作用，导致T1DM中β细胞抑制和死亡的假设。具体目的是：1)表征促炎细胞因子在人胰岛和胰岛素释放β细胞中的12LO活化和诱导。研究12LO通路介导细胞因子诱导的β细胞功能障碍和死亡的作用和机制。人类胰岛中特定类型的12LO将被描述。使用核酶或过表达分子抑制12LO对细胞因子信号传导和作用的影响将被测试。2)确定12LO在自身免疫性糖尿病细胞因子介导的β细胞破坏中的作用。在自身免疫性糖尿病NOD小鼠中监测12LO表达和脂质过氧化产物。细胞因子敏感性和细胞因子信号传导过程将在12LO-null小鼠中确定。我们还将进一步研究在NOD背景下生成的12-null小鼠。将测试糖尿病的发病率、胰岛素的严重程度和细胞因子对孤立胰岛的影响。12LO基因靶向减少自身免疫β细胞破坏的机制将被评估。我们还将在这些小鼠中确定12LO消耗后被破坏的炎症信号通路。3)以自发性糖尿病NOD小鼠为受体，研究12LO基因靶向对胰岛移植物存活率的影响。供体胰岛将来自12LO缺失小鼠和野生型小鼠胰岛，并经12LO核酶处理。移植物存活和自身免疫损伤的减少将被研究。这项完成的提案的结果将促进我们对引起自身免疫β细胞破坏的炎症过程的理解。这些发现应该提供新的方法来保存β细胞团，最终导致新的治疗方式来预防T1DM，并通过胰岛移植提高逆转T1DM的能力。

DESCRIPTION (provided by applicant): Autoimmune-mediated pancreatic beta-cell damage is central to the development of type 1 diabetes (T1DM) and its recurrence in islet transplant recipients. Proinflammatory cytokines and lipid mediators are important contributors to beta-cell damage. We have focused on the role of arachidonic acid metabolism by 12-Lipoxygenase (12LO) in leading to immune-mediated beta-cell destruction. 12LO can be activated and induced by proinflammatory cytokines. 12LO metabolites can initiate intracellutar signaling cascades leading to beta-cell dysfunction and death. In this proposal, we will test the hypothesis that the 12LO pathway plays a key role in autoimmunity-mediated inflammatory responses leading to beta-cell inhibition and death in T1DM. The specific aims are: 1) to characterize 12LO activation and induction by proinflammatory cytokines in human islets and in insulin-releasing beta-cells. Study the role and mechanism of how the 12LO pathway mediates cytokine-induced beta-cell dysfunction and death. The particular type of 12LO in human islets will be characterized. The effect of molecular inhibition of 12LO using a ribozyme or over-expression on cytokine signaling and action will be tested. 2) to define the role of 12LO in cytokine-mediated beta-cell destruction in autoimmune diabetes. 12LO expression and lipid peroxide production will be monitored in autoimmune diabetic NOD mice. Cytokine-susceptibility and cytokine signaling processes will be determined in a 12LO-null mouse. We will also further study 12-null mouse generated on NOD background. Diabetes incidence, severeness of insulitis and cytokine effects on isolated islets will be tested. Mechanism of 12LO gene targeting reduces autoimmune beta-cell destruction will be evaluated. We will also identify the inflammatory signaling pathways disrupted upon 12LO depletion in these mice. 3) Effect of 12LO gene targeting on improving islet graft survival will be studied utilizing spontaneously diabetic NOD mice as recipients. Donor islets will be from 12LO null mice as well as the wild type mouse islets-treated with the 12LO ribozyme. Graft survival and reduction in autoimmune damage will be studied. The results from this completed proposal will advance our understanding of the inflammatory processes causing autoimmune beta-cell destruction. The findings should provide new methods to preserve beta-cell mass ultimately leading to new therapeutic modalities to prevent T1DM and improve ability to reverse T1DM using islet transplantation.