Biochemical Mechanism of Beta-Cell Destruction

项目摘要/摘要 自身免疫性糖尿病的特征是胰岛及其周围的炎症反应，即 然后选择性地破坏产生胰岛素的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促进自身免疫性糖尿病的发展。 B细胞功能受损，β细胞质量减少。为了支持这一假设，用IL-1治疗胰岛 单独或与干扰素-g和/或肿瘤坏死因子联合使用会抑制胰岛素的分泌和氧化。 新陈代谢，诱导dna损伤和β细胞活力的丧失，这是由诱导型一氧化氮合酶表达和 β细胞产生一氧化氮。30多年来，人们一直密切关注于确定 IL-1损伤β细胞的机制，但几乎没有直接证据支持IL-1在 自身免疫性糖尿病的发展。胰腺β细胞终末分化能力有限 自我更新还会产生一种对生物体生存至关重要的荷尔蒙(胰岛素)。IL-1是一种致热细胞因子 众所周知，这会在感染和受伤期间引发发烧和炎症。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糖尿病，因为90%的血量 进入胰腺的物质穿过胰岛(占胰腺湿重的1%)，从而 在感染和损伤期间，β-细胞会沐浴在IL-1中。此应用程序将测试以下假设：存在 IL-1信号在β细胞中的生理作用，旨在保护这些细胞免受迫在眉睫的危险或 侮辱。通过了解细胞因子对β的损伤和保护作用之间的微妙平衡- 细胞功能和存活，我们希望阐明IL-1信号的生理和病理生理作用 在β细胞中。有三个目的将检验以下假设：1)硫氧还蛋白/过氧化还蛋白抗氧化剂 系统保护B细胞不受活性氧和氮物种的影响；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来减弱DNA损伤反应(DDR)信号，并 降低ATP和NAD水平；3)IL-1信号促进适应性保护反应 内分泌细胞。许多生化、分子、免疫学、细胞生物学和转基因技术 将被用来研究一氧化氮及其活性中间体所通过的细胞通路 参与保护β-细胞免受损害。人们希望对控制这一事件的机制的洞察 这些研究获得的细胞因子刺激后β细胞中激活的保护性反应将 影响旨在激活b细胞保护通路的治疗策略的设计，作为一种机制 在糖尿病发展或糖尿病复发期间限制功能β-细胞团的丧失 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.