Prevention of Diabetes with Lipid Immunomodulators

描述（由申请人提供）： 近年来，CD 1d限制性自然杀伤T细胞（NK T细胞）已被确定为调节性T细胞的关键群体，其功能是控制自身免疫反应。这些细胞的缺陷被认为是1型糖尿病中自身免疫性胰岛β细胞破坏进展的促成因素，在人类和非肥胖糖尿病（NOD）小鼠中均是如此。一种称为KRN 7000的合成糖脂，是α-半乳糖基神经酰胺（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，KRN 7000通过刺激NK T细胞产生保护性Th 2型细胞因子如IL-4来发挥其有益作用。然而，KRN 7000还通过NK T细胞以及树突状细胞和自然杀伤细胞的二次刺激触发Th 1型细胞因子的产生。这可能会限制其在与有害的Th 1炎症反应相关的疾病（如1型糖尿病）中的治疗效果。Porcelli博士的实验室最近发现了alphaGalCer的结构类似物，这些类似物刺激NK T细胞的反应改变，例如优先分泌Th 2细胞因子，而不同时分泌Th 1细胞因子。我们的中心假设是具有增强的刺激Th 2细胞因子产生的能力的α GalCer类似物在糖尿病预防中将具有比α GalCer甚至更大的治疗功效，并且α GalCer及其类似物的有益作用至少部分是由于对胰岛β细胞自身抗原特异性的细胞毒性T淋巴细胞（CTL）的抑制。在这种合作伙伴关系中，主要研究人员（Porcelli和DiLorenzo博士）将共同努力，以确定NK T细胞的糖脂激活剂，这些激活剂可有效阻断或逆转1型糖尿病NOD小鼠模型中自身免疫介导的胰岛破坏。将分析这些糖脂改变自身反应性T细胞的库和效应子功能的机制，并开发优化这些潜在治疗剂在体内使用的治疗方案。因此，该项目将结合联合收割机DiLorenzo博士在NOD模型中T细胞反应和疾病进展分析方面的专业知识与Porcelli博士在糖脂化学，CD 1和NK T细胞生物学领域的专业知识。具体目标是：（1）测试引发NK T细胞应答改变的新型α GalCer类似物预防或逆转NOD小鼠中糖尿病的能力;（2）评估这些α GalCer类似物促进糖尿病NOD小鼠中同系胰岛移植物存活的能力;（3）确定体内类似物治疗对CD 1d限制性NK T细胞的数量、分布和功能的影响;（4）评估α GalCer类似物对致糖尿病β细胞毒性CD 8 + T细胞的活化、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.