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（T1 DM）及其复发的关键。促炎细胞因子和脂质介质是β细胞损伤的重要贡献者。我们集中在花生四烯酸代谢的12-脂氧合酶（12 LO）在导致免疫介导的β细胞破坏的作用。12 LO可被促炎细胞因子激活和诱导。12 LO代谢物可引发细胞内信号级联，导致β细胞功能障碍和死亡。在本提案中，我们将检验12 LO通路在自身免疫介导的炎症反应中发挥关键作用的假设，导致T1 DM中β细胞抑制和死亡。具体目标是：1）表征人胰岛和胰岛素释放β细胞中促炎细胞因子的12 LO活化和诱导。研究12 LO通路如何介导马槟榔碱诱导的β细胞功能障碍和死亡的作用和机制。将表征人胰岛中12 LO的特定类型。将测试使用核酶或过表达对12 LO的分子抑制对细胞因子信号传导和作用的影响。2)以确定12 LO在自身免疫性糖尿病中甘氨酸介导的β细胞破坏中的作用。将在自身免疫性糖尿病NOD小鼠中监测12 LO表达和脂质过氧化物产生。将在12 LO-无效小鼠中测定细胞因子易感性和细胞因子信号传导过程。我们还将进一步研究NOD背景下产生的12-null小鼠。将测试糖尿病发病率、胰岛炎的严重性和细胞因子对分离的胰岛的影响。将评价12 LO基因靶向减少自身免疫β细胞破坏的机制。我们还将确定在这些小鼠中12 LO耗尽后破坏的炎症信号通路。3)将利用自发性糖尿病NOD小鼠作为受体研究12 LO基因靶向对改善胰岛移植物存活的作用。供体胰岛将来自12 LO无效小鼠以及用12 LO核酶处理的野生型小鼠胰岛。将研究移植物存活和自身免疫损伤的减少。这个完整提案的结果将促进我们对导致自身免疫性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护β细胞群，最终导致新的治疗方式来预防T1 DM和提高使用胰岛移植逆转T1 DM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.