Complement in the Vascular Complications of Diabetes

描述(由申请人提供)： 这项建议的主要目标是研究糖化的人CD59作为血管糖尿病并发症的替代生物标志物和预测因子，特别关注糖尿病肾病以及周围和心血管疾病。CD59是一种关键的补体调节膜蛋白，它特异性地抑制补体膜攻击复合体(MAC)的形成，MAC是一个跨膜孔，触发生长因子和细胞因子的释放，刺激细胞增殖、炎症和血栓形成。人CD59通过糖基化失活，因为它的活性部位含有由氨基酸残基K41-H44形成的糖基化基序，这是通过对人CD59结构的核磁共振分析和定点突变研究确定的。我们提出，CD59的糖基化失活首先导致糖尿病组织中MAC沉积增加，然后MAC诱导的生长因子和细胞因子的释放增加，这些生长因子和细胞因子与其他高血糖诱导的途径协同作用，促进导致人类糖尿病血管并发症的各种组织损伤。与这一假设一致，糖尿病患者的肾小球、神经、血管和失败的静脉移植中发现了糖化的CD59和激活的补体蛋白，包括MAC，而非糖尿病患者则没有。重要的是，我们已经证明了可溶性形式的CD59，包括糖化和非糖化的，可以通过建立的ELISA在人的尿液和血浆中检测到。糖化CD59水平似乎与血糖暴露水平相关。这些广泛的初步数据使得评估糖化CD59是否代表糖尿病血管并发症的致病相关生物标志物是必要的。具体地说，我们将研究血浆和/或尿中的糖化CD59是否识别出糖尿病血管并发症的风险亚群(特定目标1)，区分有较高心血管疾病风险的糖耐量受损人群(特定目标2)，并预测发生糖尿病肾病的风险(特定目标3)和/或周围血管旁路手术后静脉移植失败的风险(特定目标4)。这些特定目标的成功实现将为糖尿病血管并发症提供一个新的生物标志物，也将为糖尿病并发症的早期治疗甚至预防开辟新的途径。

DESCRIPTION (provided by applicant): The major goal of this proposal is to investigate glycated human CD59 as a surrogate bio-marker and predictor of vascular diabetic complications, with special focus on diabetic nephropathy and peripheral and cardio-vascular disease. CD59 is a key complement regulatory membrane protein that specifically inhibits formation of the membrane attack complex of complement (MAC), a transmembrane pore that triggers the release of growth factors and cytokines that stimulate cell proliferation, inflammation and thrombosis. Human CD59 is inactivated by glycation because it contains in its active site a glycation motif formed by amino acid residues K41-H44, as determined by NMR analysis of the human CD59 structure and site directed mutagenesis studies. We proposed that glycation-inactivation of CD59 leads first to increased MAC deposition in diabetic tissues and then to increased MAC-induced release of growth factors and cytokines that synergistically with other hyperglycemia induced pathways promote the diverse tissue damage responsible for the vascular complications that characterize human diabetes. Consistent with this hypothesis, glycated CD59 and activated complement proteins including MAC are found in glomeruli, nerves, blood vessels and failed vein grafts from diabetic but not from nondiabetic patients. Importantly, we have shown that a soluble form of CD59, both glycated and non-glycated, can be measured in human urine and plasma by established ELISAs. Glycated CD59 levels seem to correlate with the level of glycemic exposure. These extensive preliminary data make it imperative to assess whether glycated CD59 represents a pathogenically relevant biomarker of diabetic vascular complications. Specifically we will investigate whether glycated CD59 in plasma and/or urine identifies sub-populations at risk of developing vascular complications of diabetes (Specific Aim 1), discriminates persons with impaired glucose tolerance who have a higher risk of cardiovascular disease (Specific Aim 2), and predicts the risk of developing diabetic nephropathy (Specific Aim 3) and/or the risk of vein graft failure after peripheral by-pass surgery (Specific Aim 4). Successful accomplishment of these Specific Aims will provide a novel biomarker of diabetic vascular complications; it will also open new avenues for the early treatment and perhaps prevention of those diabetic complications.