NITRIC OXIDE AND INSULIN IN ISLET TRANSPLANTATION

本研究的目的是提高临床胰岛治疗的成功率。 移植。提出了两个相互关联的假设以实现 这个目标。首先，一氧化氮(NO)被认为是质数 胰岛功能障碍的中介物。第二，之前未被承认的 胰岛素减少NO生成的能力被认为是解释其 保护胰岛的活动。这两个假设都将得到检验。 直接通过将本调查中的实验集中在使用 诱导型一氧化氮合酶基因敲除小鼠(iNOS-/-)。特定的 目的探讨巨噬细胞一氧化氮在胰岛移植中的作用。 拒绝。根据这项研究的初步和公开结果 实验室，NO被提出在两个“波”中抑制胰岛：一种早期波 发生在同基因或异基因胰岛移植后1-2天 导致早期胰岛功能障碍。无中介的第二波浪潮 胰岛功能障碍被认为发生在经典的同种异体移植中。 拒绝。将通过比较同源基因来研究早期波 糖尿病小鼠iNOS-/-和iNOS-/+的胰岛功能；第二波 将在这些宿主中使用同种异体胰岛进行研究。抗肿瘤药物 然后将使用否来确定如何最好地增加胰岛功能。 来自该实验室的初步和已公布的证据表明 以一种临床适用的方式抑制NO确实增加了 胰岛移植。胰岛将被植入腹膜内 空洞的调查是因为移植物内没有产生 在这个部位可以很容易地观察到同种异体移植排斥反应。老鼠 将是主要使用的物种，因为和人类一样，他们是“低等的”。 NO的生产者；老鼠将被用于选定的实验，因为 他们的大号。特殊目标II将通过以下方式确定机制 胰岛素能促进胰岛功能。一个占主导地位的范例是 这种胰岛素可以让移植的贝塔细胞“休息”。然而， 初步证据表明，糖尿病患者服用胰岛素 小鼠或大鼠降低巨噬细胞iNOS mRNA表达和NO 制作。因此，具体的实验将再次比较iNOS- /-和iNOS-/+小鼠，直接测试胰岛- 胰岛素的保护作用是通过减少NO的产生来实现的。 最后，将使用高血糖钳来维持 高血糖，以确定是否有胰岛保护活性 胰岛素依赖于它的降血糖能力。结果是 这项调查应该会提供重要的新信息， 提高临床胰岛移植的成功率 关于一氧化氮在细胞排斥反应中所起作用的基本信息 移植，以及胰岛素如何调节一氧化氮的产生。

The goal of this investigation is to increase the success of clinical islet transplantation. Two interrelated hypotheses are put forth to achieve this goal. First, Nitric Oxide (NO) is postulated to be a prime mediator of islet dysfunction. Second, a previously unrecognized ability of insulin to decrease NO production is proposed to explain its islet-protective activity. Both of these hypotheses will be tested directly by focusing the experiments in this investigation on the use of inducible Nitric Oxide Synthase "knockout" mice (iNOS-/-). Specific Aim I will determine the role of macrophage NO in islet graft rejection. Based on preliminary and published results from this laboratory, NO is proposed to inhibit islets in 2 "waves": an early wave that occurs 1-2 days posttransplant of syngeneic or allogeneic islets is responsible for early islet dysfunction. A second wave NO-mediated islet dysfunction is proposed to occur during classical allograft rejection. The early wave will be investigated by comparing syngeneic islet function in diabetic iNOS-/- and iNOS-/+ mice; the second wave will be investigated using allogeneic islets in these hosts. Inhibitors of NO will then be used to determine how to best increase islet function. Preliminary and published evidence from this laboratory suggests that inhibiting NO in a clinically applicable way does increase the success of islet transplantation. Islets will be implanted in the intraperitoneal cavity in this investigation because intragraft NO production and allograft rejection responses can readily be followed at this site. Mice will be the primary species used because, like humans, they are "low" producers of NO; rats will be used in selected experiments because of their larger size. Specific Aim II will determine the mechanism by which insulin promotes islet function. A dominant paradigm has been that insulin allows transplanted beta-cells to "rest". However, preliminary evidence indicates that insulin administration to diabetic mice or rats decreases macrophage iNOS mRNA expression and NO production. Therefore, specific experiments will again compare iNOS- /- and iNOS-/+ mice to directly test the hypothesis that the islet- protective activity of insulin results from decreasing NO production. Finally, hyperglycemic clamps will be employed to maintain hyperglycemia in order to determine if the islet-protective activity of insulin depends on its ability to lower blood glucose. The results of this investigation should provide important new information that will increase the success of clinical islet transplantation as well as providing basic information on what role NO plays in rejection of cell transplants, and how NO production is regulated by insulin.