Adaptive epigenetic mechanisms of beta and immune cells in autoimmune diabetes

项目摘要 1型糖尿病（T1 D）是一种慢性自身免疫性疾病，其导致产生胰岛素的β细胞的破坏 在临床表现之前和之后的几年内。然而，并不是所有的β细胞都被杀死，因为以下- 对长期存在T1 D的个体的研究已经确定了即使在T1 D治疗后数年仍有残余胰岛素产生。 疾病的发作。基于这些和其他观察，这项工作的前提是， β细胞对免疫攻击的反应，可以防止它们的破坏。我们之前发现， 一些β细胞经历“去分化”，表达较低水平的β细胞转录因子， 免疫原性，并被保护免于杀死。本提案的总体目标是确定适应性变化 并利用这些信息来增强它们在免疫攻击环境中的生存。我们发现 在人和鼠β-内酰胺酶基因组中，表观基因组修饰物如DNMT 3a和Tet 2的表达增加， 在体外，在暴露于炎性细胞因子期间，或在体内在自身免疫期间。我们发现， 来自患有自身免疫性胰腺炎和nPOD样品中T1 D的人的胰岛中β细胞中TET 2的表达。 然而，从我们对NOD小鼠糖尿病进展过程中β细胞的分析来看，那些抵抗自身免疫的β细胞， 杀有降低Tet 2的表达。Tet 2诱导甲基化CpG位点的羟甲基化， 将抑制性表观遗传标记转化为允许性表观遗传标记的第一步我们创建了Tet 2-/- NOD小鼠， 转移研究，骨髓移植和直接培养与炎性细胞因子和糖尿病 免疫细胞显示Tet 2的缺失阻止β细胞的自身免疫杀伤。我们的数据表明， Tet 2缺陷的β细胞不仅对免疫杀伤具有抗性，而且还改变自身免疫应答。我们 假设Tet 2可以修饰β细胞并影响其对自身免疫杀伤敏感性，并计划对此进行测试 在小鼠模型系统和人细胞中的假设。我们将在单细胞基础上分析转录组 和来自WT和Tet 2-/-小鼠的β细胞的表观基因组（通过ATACseq）。我们将鉴定DNA结合序列 Tet 2在β细胞中的表达明确Tet 2在β细胞中的作用，并确定其与时间的关系。 Tet 2表达和对杀死的易感性的研究，我们将产生Tet 2组织特异性缺失的小鼠，并诱导 在T1 D的发展过程中有时会出现缺失。我们将分析Tet 2中免疫细胞的差异 足够的和-/-小鼠。在第二个目标中，我们将分析TET 2表达和相关基因表达， 来自nPOD、自身免疫性胰腺炎患者和对照的人类样本中的表观遗传特征 科目最后，我们将评估TET 2表达在人胚胎干细胞衍生的β细胞中的作用， 而在体外和移植到小鼠体内后没有TET 2表达。这些研究将决定 TET 2可以控制β细胞对免疫攻击的反应的机制，并可能确定预防β细胞免疫攻击的途径。 其销毁适用于临床环境。

Project Summary Type 1 diabetes (T1D) is a chronic autoimmune disease that lead to the destruction of insulin producing β cells over a period of years before clinical presentation and afterwards. However, not all β cells are killed since follow- up studies of individuals with long standing T1D have identified residual insulin production even years after the onset of disease. The premise of this work, based on these and other observations, is that there are adaptive responses of the β cells to the immunologic attack that may prevent their destruction. We previously found that some β cells undergo “dedifferentiation”, express lower levels of β cell transcription factors, have reduced immunogenicity, and are protected from killing. The overall goal of this proposal is to identify adaptive changes in β cells and use this information to enhance their survival in the setting of immune attack. We found that there was increased expression of modifiers of the epigenome such as DNMT3a and Tet2 in human and murine β cells in vitro, during exposure to inflammatory cytokines, or in vivo during autoimmunity. We found increased expression of TET2 in β cells in islets from humans with autoimmune pancreatitis and T1D in nPOD samples. However, from our analysis of β cells during diabetes progression in NOD mice, those that resist autoimmune killing have decreased expression of Tet2. Tet2 induces hydroxymethylation of methylated CpG site which is the first step in converting a repressive to permissive epigenetic mark. We created Tet2-/- NOD mice and in adoptive transfer studies, bone marrow transplants and direct cultures with inflammatory cytokines and diabetogenic immune cells showed that deletion of Tet2 prevents autoimmune killing of β cells. Our data indicates that the Tet2-deficient β cells are not only resistant to immune killing but also modify the autoimmune responses. We hypothesize that Tet2 can modify β cells and affect their susceptibility to autoimmune killing and plan to test this hypothesis in murine model systems and human cells. We will analyze on a single cell basis the transcriptome and epigenome (by ATACseq) of β cells from WT and Tet2-/- mice. We will identify the DNA binding sequences of Tet2 in β cells. To specifically identify the role of Tet2 in β cells and determine the relationship between timing of Tet2 expression and susceptibility to killing we will create mice with tissue specific deletion of Tet2 and induce the deletion at times throughout the development of T1D. We will analyze the differences in immune cells in Tet2 sufficient and -/- mice. In the 2nd aim we will analyze TET2 expression and associated gene expression and epigenetic signatures in human samples from nPOD, patients with autoimmune pancreatitis, and control subjects. Finally, we will assess the role of TET2 expression in human embryonic stem cell-derived- β cells with and without TET2 expression in vitro and after transplantation into mice. These studies will determine the mechanisms whereby TET2 can control β cell responses to immune attack and may identify a pathway to prevent their destruction that is applicable to clinical settings.