Protein carbamylation and uremic cardiomyopathy in chronic kidney disease

项目总结/摘要 越来越多的证据表明，蛋白质修饰尿素（氨甲酰化）有助于尿毒症 心肌病和死亡率。我们最近开发了一种检测氨甲酰化白蛋白（C-Alb）的方法， 类似于“血红蛋白A1 c用于尿毒症”我们已经证明，C-Alb值是心力衰竭风险的预测指标。 血液透析患者的心脏原因和死亡，氨基酸缺乏是关键 氨甲酰化的决定因素，和C-Alb可以减少氨基酸清除剂治疗。此外，委员会认为， 在小鼠中通过尿素的过度氨甲酰化足以诱导小鼠的心脏功能障碍。这项建议旨在 研究C-Alb是否也能预测慢性肾脏疾病患者在开始治疗前的结局 透析治疗，以便将该测试的临床应用扩展到早期阶段的患者， 疾病，当治疗的变化有机会防止疾病进展。第二，我们要证明 尿素对心脏的特异性毒性，并在CKD和氧化应激小鼠模型中研究其机制。 应激性心肌病目的1将检验C-Alb是一种预后生物标志物的假设 与非透析患者的死亡率、发病率、透析进展和蛋白质能量消耗相关 2-5期慢性肾病患者。目标1将进一步比较C-Alb与 为了探讨C-Alb是否可能是尿毒症的上级适应症， 早期开始透析，并将检验高C-Alb与特定的 氨基酸和其他必需营养素，其代表靶向营养疗法的候选物。目的2 将寻求开发控制良好的尿素诱导心肌病小鼠模型，以证明直接 尿素对心脏的毒性，并研究潜在的机制。我们的假设是， 通过向肾功能降低的小鼠或对以下物质敏感的小鼠喂食尿素增加循环尿素 心脏线粒体氧化应激将产生心肌病和心力衰竭， 慢性肾病患者。目标2（a）将利用诱导性肾脏的POD-ATTAC小鼠模型 将在其饮食中喂食尿素以测试高尿毒症对肾功能的影响 不足对照动物将接受类似的足细胞消融治疗，但饲喂正常饮食。动物将 通过超声心动图监测心脏功能的差异，并研究心肌 介导尿素毒性的信号通路。目标2（B）将利用具有心脏特异性免疫抑制剂的小鼠模型。 PGC-1α辅激活因子缺乏。这些动物患有心脏线粒体氧化应激增加 容易患上压力诱发的心肌病向这些动物饲喂尿素将测试以下物质的贡献： 尿素对心脏氧化应激和肌病的影响，进一步分离了 尿素对心脏的影响

PROJECT SUMMARY/ABSTRACT There is growing evidence that protein modification by urea (carbamylation) contributes to uremic cardiomyopathy and mortality. We recently developed an assay for carbamylated albumin (C-Alb), a blood test similar to “hemoglobin A1c for uremia.” We have shown that C-Alb values are predictive of risk of heart failure and death from cardiac causes in patients on hemodialysis and that amino acid deficiencies are critical determinants of carbamylation, and C-Alb can be reduced by amino acid scavenger therapy. Moreover, hypercarbamylation by urea in mice is sufficient to induce cardiac dysfunction in mice. This proposal seeks to investigate whether C-Alb also predicts outcomes in patients with chronic kidney disease prior to initiation of dialysis therapy in order to extend the clinical applications of this test to patients in the earlier stages of disease, when changes in treatment have a chance to prevent disease progression. Second, we want to prove the specific toxicity of urea on the heart and investigate its mechanisms in mouse models of CKD and oxidative stress-associated cardiomyopathy. AIM 1 will test the HYPOTHESIS that C-Alb is a prognostic biomarker associated with mortality, morbidity, progression to dialysis, and protein energy wasting in non-dialyzed patients with stages 2-5 chronic kidney disease. Aim 1 will further compare the risk associated with C-Alb to that of standard clinical indicators of uremia in order to probe whether C-Alb may be a superior indication of early initiation of dialysis, and will test the hypothesis that high C-Alb is associated with deficiencies of specific amino acids and other essential nutrients which represent candidates for targeted nutritional therapies. AIM 2 will seek to develop well controlled mouse models of urea-induced cardiomyopathy in order to prove the direct toxicity of urea on the heart and to study potential mechanisms. Our HYPOTHESIS is that inducing isolated increases in circulating urea by feeding urea to mice with reduced kidney function or to mice with sensitivity to cardiac mitochondrial oxidative stress will produce cardiomyopathy and heart failure similar to that seen in patients with chronic kidney disease. Aim 2(a) will utilize the POD-ATTAC mouse model of inducible kidney failure mice which will be fed urea in their diet to test the effects of hyperuremia superimposed upon renal insufficiency. Control animals will be similarly treated with podocyte ablation but fed normal diets. Animals will be monitored by echocardiography for differences in cardiac function, and studied for differences in myocardial signaling pathways which mediate urea's toxicity. Aim 2(b) will utilize a mouse model with a cardiac-specific deficiency of PGC-1α coactivator. These animals suffer from increased cardiac mitochondrial oxidative stress and are prone to stress-induced cardiomyopathy. Feeding urea to these animals will test the contribution of urea to cardiac oxidative stress and myopathy in an animal with normal kidney dysfunction, further isolating the effect of urea on the heart.