Role of Complex Sphingolipids in Diabetic Neuropathy

项目摘要/摘要 糖尿病神经病变是一种令人痛苦和虚弱的疾病，50%的糖尿病患者会受到影响。尽管 其高患病率、糖尿病肾病的确切生物学机制尚不清楚，目前尚无疾病阻断治疗。 目前可用。因此，迫切需要确定治疗目标和预防措施。 域名系统的策略。最近的数据显示，在2型糖尿病(T2D)中，鞘磷脂代谢发生了变化，导致 非典型的、具有神经毒性的脱氧鞘磷脂(DSL)的堆积。已知DSL在以下情况下会增加 低水平的氨基酸L-丝氨酸和高水平的L-丙氨酸，但糖尿病患者DSL堆积的原因是 不知道。重要的是，口服补充氨基酸L-丝氨酸可以抑制dsls的形成和 改善糖尿病肾病动物模型的神经病变，提示dsls可能在糖尿病肾病中发挥作用。建议进行的研究 目的是定义与糖尿病肾病关系最密切的特定DSL分子，并评估 改变了L-丙氨酸/L-丝氨酸的比率，使DSL在T2D中积累。定义DSL中的特定分子 与糖尿病肾病关系最密切的途径，并了解其形成原因可能 导致制定针对该疾病的针对性治疗干预措施。 先进的质谱学技术已经被用来证明选定的DSL(1-2)的高度 脱氧二氢神经酰胺)在一小群患有病态肥胖症、T2D和糖尿病肾病的成人队列中。结果显示：1)L- 与对照组相比，糖尿病肾病患者的丝氨酸水平降低，L-丙氨酸水平升高； 升高的L-丙氨酸/L-丝氨酸比值与DSLS及糖尿病肾病严重程度呈正相关。在目标1中 拟议的研究，将使用相同最先进的技术来检查详细的DSL简档和氨基酸 青少年和青年T2D治疗方案的横断面和纵向水平(目前) 一群人。这些研究将检验L-丙氨酸和L-丝氨酸的比率是否与糖尿病患者的DSL堆积有关 青年发病T2D的横断面比较(目标1a)；并测试L-丙氨酸到L-丝氨酸的升高 通过一项回顾性病例对照研究，比率和dsl与发生糖尿病肾病的几率增加相关。 设计(目标1b)。在目标2中，dsl和L-丙氨酸/L-丝氨酸比率与糖尿病肾病严重程度的相关性如下 在科罗拉多大学的成人T2D队列(没有病态肥胖的混杂因素)中进行检查，使用 经过验证的糖尿病肾病指标包括皮肤活检中的神经纤维密度。 K23赠款将允许候选人在1)针对糖尿病肾病的临床结果衡量标准方面进行培训，2) 流行病学原理和统计方法；3)脂类生物学和质谱学基础。这个 简·鲁施博士、罗伯特·墨菲博士、布莱恩·伯格曼博士、伊娃·费尔德曼博士和莱斯利·兰格博士的指导和建议， 其专业知识横跨内分泌学、糖尿病肾病、流行病学和脂质生物学，非常适合这一项目。这个 科罗拉多大学丹佛分校拥有领先的临床研究，为这项工作提供了最佳的环境 T2D计划，以及支持初级调查人员的广泛基础设施。

PROJECT SUMMARY/ABSTRACT Diabetic neuropathy (DN) is a painful and debilitating condition that affects 50% of people with diabetes. Despite its high prevalence, the precise biological mechanisms of DN are not known and no disease arresting treatment is currently available. There is therefore a critical need for the identification of therapeutic targets and preventative strategies for DN. Recent data show that sphingolipid metabolism is altered in type 2 diabetes (T2D), resulting in the accumulation of atypical, neurotoxic deoxysphingolipids (dSLs). dSLs are known to increase in the setting of low levels of the amino acid L-serine and high levels of L-alanine, but the cause of dSL accumulation in diabetes is not known. Importantly, oral supplementation with the amino acid L-serine suppresses formation of dSLs and improves neuropathy in animal models of DN, suggesting that dSLs could play a role in DN. The proposed study aims to define the specific dSL molecules that are most closely associated with DN and evaluate the contribution of altered L-alanine to L-serine ratios to dSL accumulation in T2D. Defining the specific molecules in the dSL pathway that are most closely associated with DN and understanding the cause for their formation could lead to the development of targeted therapeutic interventions for the disease. Advanced mass spectrometry techniques have been used to demonstrate elevations in select dSLs (1- deoxydihyroceramides) in a small cohort of adults with morbid obesity, T2D and DN. Results showed that 1) L- serine levels were lower and L-alanine levels higher in subjects with DN as compared to controls; and 2) that increased L-alanine to L-serine ratios correlated positively with dSLs and with DN severity. In Aim 1 of the proposed studies, the same state of the art techniques will be used to examine detailed dSL profiles and amino acid levels cross-sectionally and longitudinally in the Treatment Options for T2D in Adolescents and Youth (TODAY) cohort. These studies will examine whether L-alanine to L-serine ratios are associated with dSL accumulation in youth onset T2D in a cross sectional comparison (Aim 1a); and test whether elevations in L-alanine to L-serine ratios and dSLs are associated with an increased odds of developing DN using a retrospective case-control study design (Aim 1b). In Aim 2, correlations between dSLs and L-alanine to L-serine ratios to DN severity will be examined in an adult T2D cohort (without the confounder of morbid obesity) at the University of Colorado using validated DN measures including nerve fiber density on skin biopsy. The K23 grant will allow the candidate to pursue training in 1) clinical outcome measures specific to DN, 2) epidemiologic principles and statistical methods, and 3) fundamentals of lipid biology and mass spectrometry. The mentorship and advising of Drs. Jane Reusch, Robert Murphy, Bryan Bergman, Eva Feldman, and Leslie Lange, whose expertise spans endocrinology, DN, epidemiology and lipid biology, is ideally suited for this project. The University of Colorado Denver offers the optimal environment for this work, with a leading clinical research program in T2D, and extensive infrastructure for supporting junior investigators.