Biochemical Mechanism of Beta-Cell Destruction

项目总结/摘要 自身免疫性糖尿病的特征在于胰岛内和周围的炎症反应， 随后选择性破坏产生胰岛素的β细胞。传统观点认为， 在胰岛炎症过程中释放的细胞因子，通过直接作用促进自身免疫性糖尿病的发展。 削弱B细胞功能并减少β细胞质量。为了支持这一假设，用IL-1处理胰岛 单独或与IFN-g和/或TNF组合，导致胰岛素分泌和氧化抑制， 在某些实施方案中，诱导细胞代谢、诱导DNA损伤和由iNOS表达介导的β细胞活力丧失，以及诱导细胞凋亡。 β细胞产生一氧化氮。30多年来，人们一直非常关注确定 IL-1损伤β细胞的机制，但几乎没有直接证据支持IL-1在β细胞中的作用。 自身免疫性糖尿病胰腺β细胞是终末分化的，具有有限的分化能力。 自我更新还产生一种对生物体生存至关重要的激素（胰岛素）。IL-1是一种致热性细胞因子 在感染和受伤时会引起发热和炎症。如果β细胞对IL-1的反应是 如果仅仅是破坏性的，那么大多数人都很容易患上糖尿病，因为90%的血液体积 通过胰岛（其代表胰腺湿重的1%）， 在感染和损伤过程中，β细胞将沐浴在IL-1中。这个应用程序将测试假设，有一个 IL-1信号在β细胞中的生理作用，旨在保护这些细胞免受即将发生的危险或 侮辱。通过了解细胞因子对β-内酰胺酶的损伤和保护作用之间的微妙平衡， 细胞功能和生存，我们希望阐明IL-1信号转导的生理和病理生理作用 在β细胞中。有三个目标，将测试假设：1）硫氧还蛋白/过氧化物氧还蛋白抗氧化剂 系统保护B细胞免受活性氧和氮物质的影响; 2）一氧化氮，以B细胞选择性的方式， 通过抑制线粒体氧化代谢减弱DNA损伤反应（DDR）信号传导， 降低ATP水平和NAD水平;和3）IL-1信号传导促进适应性保护反应， 内分泌细胞许多生物化学、分子、免疫学、细胞生物学和转基因技术 将用于研究一氧化氮及其活性中间体的细胞途径 参与保护β细胞免受损伤。人们希望，深入了解控制 从这些研究中获得的细胞因子刺激后β细胞中激活的保护性应答将 影响旨在激活B细胞中的保护性途径的治疗策略的设计， 在糖尿病发展或糖尿病复发期间限制功能β细胞群的丧失， 移植环境

Project Summary/Abstract Autoimmune diabetes is characterized by an inflammatory reaction in and around pancreatic islets that is followed by the selective destruction of insulin producing β-cells. The conventional wisdom suggests that cytokines, released during islet inflammation, contribute to the development of autoimmune diabetes by directly impairing b-cell function and reducing β-cell mass. In support of this hypothesis, treatment of islets with IL-1 alone, or in combination with IFN-g and/or TNF, results in an inhibition of insulin secretion and oxidative metabolism, induction of DNA damage and a loss of β-cell viability that is mediated by iNOS expression and the production of nitric oxide by β-cells. For over 30 years there has been an intense focus on determining the mechanisms by which IL-1 damages β-cells, yet there is little direct evidence supporting a role for IL-1 in the development of autoimmune diabetes. Pancreatic β-cells are terminally differentiated with a limited capacity for self-renewal yet produce a hormone (insulin) that is essential for organismal survival. IL-1 is a pyrogenic cytokine that is well known to induce fever and inflammation during infection and injury. If the β-cell response to IL-1 were solely damaging, then most individuals would be highly susceptible to diabetes, as 90 % of the volume of blood that enters the pancreas travels through islets (which represents 1% of the wet weight of the pancreas) such that β-cells would be bathed in IL-1 during infection and injury. This application will test the hypothesis that there is a physiological role for IL-1 signaling in β-cells that is designed to protect these cells from impending danger or insult. By understanding the delicate balance between the damaging and protective actions of cytokines on β- cell function and survival, we hope to elucidate the physiological and pathophysiological roles of IL-1 signaling in β-cells. There are thee aims that will test the hypotheses that: 1) the thioredoxin/peroxiredoxin antioxidant system protects b-cells from reactive oxygen and nitrogen species; 2) nitric oxide, in a b-cell selective manner, attenuates DNA damage response (DDR) signaling by inhibiting mitochondrial oxidative metabolism and decreasing the levels ATP and NAD levels; and 3) IL-1 signaling promotes an adaptive protective response in endocrine cells. A number of biochemical, molecular, immunological, cell biological, and transgenic techniques will be utilized to investigate the cellular pathways through which nitric oxide and its reactive intermediates participate in the protection of β-cells from damage. It is hoped that insights into the mechanisms controlling the protective responses activated in β-cells following cytokine stimulation that are gained from these studies will influence the design of therapeutic strategies aimed to activate protective pathways in b-cell as a mechanism to limit the loss of function β-cell mass during the development of diabetes or recurrence of diabetes in the transplantation setting.