Biochemical mechanism of beta-cell destruction

描述(申请人提供)：自身免疫性糖尿病的特征是胰岛内和胰岛周围的炎症反应，随后有选择地破坏β细胞。这项研究的主要目标是阐明与胰腺β细胞破坏相关的细胞机制，并确定β细胞保护自己免受细胞因子和自由基介导的损伤的机制。我们已经证明，一氧化氮介导了白细胞介素1(IL-1)和干扰素-γ(干扰素-γ)对β细胞功能的抑制作用。一氧化氮还激活了一条“恢复”途径，保护β细胞免受细胞因子的损害。正是这种一氧化氮的毒性和保护作用之间的微妙平衡，可能最终决定了β细胞对细胞因子介导的损伤的易感性。这项建议侧重于阐明β细胞破坏的细胞途径和从细胞因子介导的损伤中恢复。有三个具体目标。1.阐明胰岛滞留巨噬细胞活化和促炎细胞因子释放介导胰岛β细胞损伤的生化机制。拟议的实验将使用转基因方法来确定IL-1a转换酶(ICE)、IL-1受体和IL-1受体信号组件在介导胰岛微环境中巨噬细胞局部产生IL-1所刺激的β细胞损伤中的作用。2.为了验证一氧化氮和过氧化物酶体增殖物激活受体-γ的假说，激动剂激活了一条保护β细胞免受细胞因子介导的损伤的通路(S)。拟议的实验将检验一氧化氮和PPAR-γ激动剂防止细胞因子介导的β细胞损伤的机制。3.使用表达谱鉴定在与细胞因子介导的损伤中的β细胞恢复相关的条件下发生表达变化的候选基因。一旦确定，这些基因或基因产物将被表达或转导到β细胞中，以确定保护细胞免受细胞因子介导的损伤的机制。 将利用生化、分子生物学、免疫学、组织化学和转基因技术来研究一氧化氮介导β细胞破坏的细胞途径以及参与保护β细胞免受细胞因子介导的损伤的途径。希望从这些研究中获得的对细胞因子介导的损伤的机制和对这种损伤的保护的见解将影响旨在预防或治疗这种衰弱障碍的治疗策略的设计。

DESCRIPTION (provided by applicant): Autoimmune diabetes is characterized by an inflammatory reaction in and around pancreatic islets, followed by selective destruction of beta-cells. The broad goals of this research are to elucidate the cellular mechanisms associated with pancreatic beta-cell destruction and identify mechanisms by which beta-cells protect themselves against cytokine- and free radical-mediated damage. We have shown that nitric oxide mediates the inhibitory actions of interleukin-1 (IL-1) and interferon-gamma (IFN-gamma) on beta-cell function. Nitric oxide also activates a "recovery" pathway that protects beta-cells from cytokine-mediated damage. It is this delicate balance between the toxic and protective actions of nitric oxide that may ultimately determine the susceptibility of beta-cells to cytokine-mediated damage. This proposal focuses on elucidating the cellular pathways of beta-cell destruction and recovery from cytokine-mediated damage. There are three specific aims. 1. To elucidate the biochemical mechanisms by which resident macrophage activation and proinflammatory cytokine release in islets mediates beta-cell damage. Experiments proposed will use a transgenic approach to determine the role of the IL-1a converting enzyme (ICE), the IL-1 receptor, and IL-1 receptor signaling components in mediating beta- cell damage stimulated by the local production of IL-1 by macrophages in the microenvironment of the islet. 2. To test the hypothesis that nitric oxide and peroxisome proliferator-activated receptor (PPAR)-gamma, agonists activate a pathway(s) that protects beta-cells from cytokine-mediated damage. Proposed experiments will examine the mechanisms by which nitric oxide and PPAR-gamma agonists prevent cytokine-mediated beta-cell damage. 3. To use expression profiling to identify candidate genes with altered expression under conditions associated with beta-cell recovery from cytokine-mediated damage. Once identified, these genes or gene products will be expressed or transduced into beta-cells to determine the mechanisms of protection from cytokine-mediated damage. A number of biochemical, molecular biological, immunological, histochemical, and transgenic techniques will be utilized to investigate the cellular pathways through which nitric oxide mediates beta-cell destruction and the pathways that participate in the protection of beta-cells from cytokine-mediated damage. It is hoped that insights into the mechanisms of cytokine-mediated damage and protection from this damage gained from these studies will influence the design of therapeutic strategies aimed at the prevention or treatment of this debilitating disorder.