Prevention of Diabetes with Lipid Immunomodulators

描述(由申请人提供)： 近年来，CD1d限制性自然杀伤T细胞(NK T细胞)被认为是控制自身免疫反应的重要调节性T细胞。这些细胞的缺陷被认为是1型糖尿病自身免疫性胰岛β细胞破坏进展的促成因素，无论是在人类还是在非肥胖糖尿病(NOD)小鼠中都是如此。一种被称为KRN7000的合成糖脂，是α-半乳糖神经酰胺(AlphaGalCer)的一种形式，具有特异性激活NK T细胞的能力。用这种化合物治疗NOD小鼠可以显著延缓或预防糖尿病。现有数据表明，KRN7000通过刺激NK T细胞产生保护性Th2型细胞因子(如IL-4)发挥其有益作用。然而，KRN7000也通过NK T细胞以及二次刺激树突状细胞和自然杀伤细胞来触发Th1型细胞因子的产生。这可能会限制其对与有害的Th1炎症反应相关的疾病的治疗效果，如1型糖尿病。波塞利博士的实验室最近发现了AlphaGalCer的结构类似物，可以刺激NK T细胞的变化反应，例如优先分泌Th2细胞因子，而不同时分泌Th1细胞因子。我们的中心假设是，具有增强刺激Th2细胞因子产生能力的AlphaGalCer类似物在预防糖尿病方面将具有比AlphaGalCer更好的治疗效果，并且AlphaGalCer及其类似物的有益效果至少部分归因于抑制胰岛β细胞自身抗原的细胞毒性T淋巴细胞(CTL)。在这一合作伙伴关系中，首席研究人员(Porcelli博士和DiLorenzo博士)将共同努力，确定NK T细胞的糖脂激活剂，有效地阻断或逆转1型糖尿病NOD小鼠模型中自身免疫介导的胰岛破坏。这些糖脂改变自身反应性T细胞的谱系和效应器功能的机制将被分析，并将开发出在体内优化使用这些潜在治疗剂的治疗方案。因此，该项目将把DiLorenzo博士在分析NOD模型中T细胞反应和疾病进展方面的成熟专业知识与Porcelli博士在糖脂化学、CD1和NK T细胞生物学领域的专业知识结合起来。其具体目的是：(1)检测新型AlphaGalCer类似物对NOD小鼠NK T细胞反应的影响，以预防或逆转糖尿病；(2)评估这些AlphaGalCer类似物促进糖尿病NOD小鼠同基因胰岛移植存活的能力；(3)确定体内类似物治疗对CD1d限制性NK T细胞的数量、分布和功能的影响；(4)评估AlphaGalCer类似物对致糖尿病的β细胞细胞毒CD8细胞的激活、扩增和分布的影响。

DESCRIPTION (provided by applicant): In recent years, CD1d-restricted natural killer T cells (NK T cells) have been identified as a critical population of regulatory T cells that function to control autoimmune responses. Defects in these cells have been implicated as contributing factors in the progression of autoimmune islet beta cell destruction in type 1 diabetes, both in humans and in nonobese diabetic (NOD) mice. A synthetic glycolipid known as KRN7000, which is a form of alpha-galactosyl ceramide (alphaGalCer), has the capacity to specifically activate NK T cells. Treatment of NOD mice with this compound can significantly delay or prevent diabetes. Available data indicate that KRN7000 exerts its beneficial effects by stimulating NK T cells to produce protective Th2-type cytokines such as IL-4. However, KRN7000 also triggers production of Th1-type cytokines by NK T cells and by secondary stimulation of dendritic cells and natural killer cells. This could limit its therapeutic efficacy in diseases associated with a harmful Th1 inflammatory response such as type 1 diabetes. Dr. Porcelli's laboratory has recently identified structural analogues of alphaGalCer that stimulate altered responses of NK T cells, such as the preferential secretion of Th2 cytokines without concurrent Th1 cytokines. Our central hypothesis is that analogues of alphaGalCer that have an enhanced capacity to stimulate the production of Th2 cytokines will have an even greater therapeutic efficacy in diabetes prevention than alphaGalCer, and that the beneficial effects of alphaGalCer and its analogues are due at least in part to the suppression of cytotoxic T lymphocytes (CTL) specific for islet beta-cell autoantigens. In this collaborative partnership, the Principal Investigators (Drs. Porcelli and DiLorenzo) will work together to identify glycolipid activators of NK T cells that efficiently block or reverse the autoimmune-mediated destruction of pancreatic islets in the NOD mouse model of type 1 diabetes. The mechanisms by which these glycolipids alter the repertoire and effector functions of autoreactive T cells will be analyzed, and treatment protocols that optimize the use of these potential therapeutic agents in vivo will be developed. The project will thus combine Dr. DiLorenzo's established expertise in analysis of T cell responses and disease progression in the NOD model with Dr. Porcelli's expertise in the areas of glycolipid chemistry, CD1, and NK T cell biology. The Specific Aims are: (1) To test the ability of novel analogues of alphaGalCer that elicit altered response of NK T cells to prevent or reverse diabetes in NOD mice; (2) To assess the ability of these alphaGalCer analogues to promote syngeneic islet graft survival in diabetic NOD mice; (3) To determine the effects of in vivo analogue treatment on the numbers, distribution and functions of CD1d-restricted NK T cells; (4) To assess the effects of alphaGalCer analogues on the activation, expansion and distribution of diabetogenic beta-cell cytotoxic CD8+ T cells.