Vascular dysfunction and oxidative stress in primary amyloidosis

描述(申请人提供)：原发性系统性淀粉样变性是一种浆细胞异染症，通常是致命的，特别是如果有心脏受累的话。未经治疗的心力衰竭患者的中位生存期为4-8个月，但这些患者往往没有资格接受挽救生命的大剂量化疗和自体干细胞移植。它是由免疫球蛋白轻链产生的错误折叠的淀粉样蛋白沉积引起的，影响心脏、肠道、肾脏和周围神经。活组织检查研究和动物研究表明，淀粉样轻链导致氧化应激，导致结肠和心脏组织的组织损伤或功能障碍。有证据表明，早期内皮功能障碍先于淀粉样蛋白沉积，淀粉样蛋白轻链可能导致急性组织损伤。累及中小动脉的弥漫性血管功能障碍可能在导致多器官损伤中起中心作用。然而，尽管与这种疾病相关的预后很糟糕，但我们对损伤的机制知之甚少。我们的初步结果表明，非淀粉样蛋白受试者在短暂暴露于淀粉样蛋白轻链后，人类脂肪小动脉的内皮功能受损。这与超氧化物产量的增加有关。线粒体靶向抗氧化剂治疗保留了内皮功能。我们将对我们最初的观察结果进行扩展。我们计划测试我们的总体假设，即初级淀粉样轻链通过增加冠状动脉小动脉和脂肪小动脉中活性氧的产生而严重损害内皮功能。我们进一步假设线粒体是活性氧物种的来源，线粒体靶向抗氧化剂丝裂原醌的抗氧化剂治疗将保护内皮功能。为了验证这些假说，我们建议：1.测量暴露于淀粉样轻链前后人冠状动脉和脂肪小动脉(来自非淀粉样蛋白受试者)的内皮依赖性和非内皮依赖性的扩张；2.测量暴露于淀粉样轻链后冠状动脉和脂肪小动脉中的活性氧物种(超氧化物和过氧化氢)；以及3.测量丝裂霉素对暴露于淀粉样轻链后冠状动脉和脂肪小动脉内皮功能和活性氧产生的影响。这项提议既新颖又意义重大。它首次阐述了原发性淀粉样变性血管损伤和内皮功能障碍背后的机制。我们建议首次使用人类组织模型来研究这种疾病，与动物或细胞培养研究相比，这种模型将具有更相关的翻译应用。我们还将测试一种新的(丝裂酚)抗氧化剂疗法，该疗法可能会拓宽这种致命疾病的治疗选择。了解这种早期损伤背后的机制可能会让我们发现新的治疗策略，以解决全面疾病中广泛的器官损害，这种模式在其他血管损害中也可以看到，如高血糖、高血压和高脂血症。收集的信息和人类血管模型的应用可能有助于研究其他具有共同损伤机制的淀粉样疾病，如阿尔茨海默病或糖尿病。公共卫生相关性：原发性全身性淀粉样变性可能是一种致命的疾病，它是由心脏、血管、肾脏、肠道和肝脏等各种器官中异常免疫球蛋白轻链蛋白的产生和沉积引起的。淀粉样蛋白轻链损伤血管的原因尚不清楚。该项目将确定将废弃组织中的孤立人类血管暴露于淀粉样轻链是否会损害其功能，以及这种损害是否由氧化应激引起。该项目还将确定一种新型抗氧化剂丝裂原苯二酚是否会减少淀粉样轻链引起的血管功能损害。这项研究将提供有关原发性系统性淀粉样变性的基础和可能的治疗方法的重要信息，这些治疗可能会提高这些患者的存活率。

DESCRIPTION (provided by applicant): Primary systemic amyloidosis is a plasma cell dyscrasia that is often fatal especially if there is cardiac involvement. Untreated, patients with heart failure have median survival of 4-8 months, yet these patients are often ineligible for life-saving high dose chemotherapy and autologous stem cell transplantation. It results from the deposition of misfolded amyloid proteins derived from immunoglobulin light chains and affects the heart, gut, kidneys and peripheral nerves. Biopsy studies and animal studies suggest that amyloid light chains cause oxidative stress leading to tissue damage or dysfunction in colon and cardiac tissues. There is evidence that early endothelial dysfunction precedes onset of amyloid deposition and that amyloid light chains may cause acute tissue injury. Diffuse vascular dysfunction involving small and medium sized arteries may play a central role in causing multiorgan injury. Despite the grim prognosis associated with the disease, however, we know little about the mechanism of injury. Our preliminary results demonstrate impaired endothelial function in human adipose arterioles obtained from non-amyloid subjects following brief exposure to amyloid light chains. This was associated with increased superoxide production. Mitochondria targeted antioxidant treatment preserved endothelial function. We will expand on our initial observations. We plan to test our overall hypothesis that primary amyloid light chains acutely impair endothelial function by increasing reactive oxygen species production in both coronary arterioles and adipose arterioles from subjects without amyloid disease. We further hypothesize that the mitochondria is a source of reactive oxygen species and that antioxidant treatment with mitoquinone, a mitochondria targeted antioxidant will preserve endothelial function. To test these hypotheses, we propose to 1. measure endothelium-dependent and endothelium-independent dilation in isolated human coronary and adipose arterioles (from non-amyloid subjects) before and following exposure to amyloid light chains (obtained from primary amyloidosis subjects); 2. measure reactive oxygen species (superoxide and hydrogen peroxide) in coronary and adipose arterioles following exposure to amyloid light chain and 3. measure the effect of mitoquinone on endothelial function and reactive oxygen species generation in coronary and adipose arterioles following exposure to amyloid light chains. The proposal is novel and significant. It addresses for the first time the mechanism behind vascular injury and endothelial dysfunction in primary amyloidosis. We propose using a human tissue model for the first time in studying this disease that will have more relevant translational application as compared to animal or cell culture studies. We will also test a novel (mitoquinone) antioxidant therapy that may broaden management options for this fatal disease. Understanding the mechanism behind this early injury may allow us to discover new therapeutic strategies to address extensive organ damage in full-blown disease, a model that is seen in other vascular insults such as hyperglycemia, hypertension and hyperlipidemia. The information gathered and the application of the human vascular model may be useful in the study of other amyloid diseases that share common mechanisms of injury, such as Alzheimer's disease or diabetes. PUBLIC HEALTH RELEVANCE: Primary systemic amyloidosis can be a fatal disease and it is caused by the production and deposition of abnormal immunoglobulin light chain proteins in various organs such as the heart, blood vessels, kidneys, gut and liver. The cause of injury to blood vessels by amyloid light chains is unknown. The project will determine if exposure of isolated human blood vessels from discarded tissue to amyloid light chains will impair its function and whether this impairment is caused by oxidative stress. The project will also determine if mitoquinone, a novel antioxidant, will reduce the impairment in function of the blood vessel caused by amyloid light chains. The research will provide important information on the basis and possible treatment of primary systemic amyloidosis that may lead to improvement in survival in these patients.