Immunomodulatory effects of arginine supplementation in colitis and colon cancer

补充精氨酸对结肠炎和结肠癌的免疫调节作用

• 批准号: 7895707
• 负责人: Keith T. Wilson
• 金额: $ 37.67万
• 依托单位: VANDERBILT UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-09-15 至 2012-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7895707
• 关键词: Acute; Address; Adverse effects; Affect; American; Amino Acids; Apoptosis; Arginine; Attenuated; Azoxymethane; Basic Amino Acid Transport Systems; Biological; Body Weight decreased; Carrier Proteins; Cell physiology; Cells; Chronic; Citrobacter rodentium; Clinical; Colitis; Colon; Colon Carcinoma; Colonic Neoplasms; Crohn' s disease; Data; Disease; Effectiveness; Environment; Epithelial; Epithelial Cells; Equilibrium; Frequencies; Generations; Histology; Human; Immune response; Immunity; Immunobiology; Immunology; In Vitro; Inflammation; Inflammatory; Inflammatory Bowel Diseases; Inflammatory disease of the intestine; Lead; Lymphocyte; Malignant Neoplasms; Metabolic Pathway; Metabolism; Microbe; Modeling; Morbidity - disease rate; Mucositis; Mus; Nitric Oxide; Nitric Oxide Synthase; Ornithine; Ornithine Decarboxylase; Outcome; Pathway interactions; Patients; Phagocytosis; Polyamines; Population; Prevention; Process; Protein Family; Proteins; Public Health; Regulation; Regulatory T-Lymphocyte; Reporting; Research Design; Rest; Risk; Role; Route; Serum; Sodium Dextran Sulfate; Source; Stimulus; Stress; Supplementation; System; Testing; Tissues; Translations; Ulcerative Colitis; Weight; Wild Type Mouse; Work; Wound Healing; arginase; arginine treatment; carcinogenesis; chemokine; colitis associated cancer; colon carcinogenesis; cost; cytokine; enzyme substrate; extracellular; human NOS2A protein; immune activation; immunoregulation; improved; in vivo; in vivo Model; insight; macrophage; mouse model; novel strategies; response; semi essential amino acid; therapy development; translational study; tumor; uptake

DESCRIPTION (provided by applicant): Inflammatory bowel disease (IBD), consisting of ulcerative colitis (UC) and Crohn's disease (CD), is a source of extensive morbidity and risk for progression to colon cancer in the US population, with more than one million Americans affected. The semi-essential amino acid L-arginine (L-Arg) has been touted as a supplement with many potential benefits including enhancement of immunity. In response to RFA AT-07-004 we will conduct mechanistic studies in mouse models to address the potential value of L-Arg as a supplement in IBD and determine if it can reduce risk for colitis-associated cancer. During conditions of immune activation, the two major routes for L-Arg utilization are the inducible nitric oxide (NO) synthase (iNOS) and arginase pathways. Arginase generates L-ornithine, the substrate for the enzyme ornithine decarboxylase (ODC) that produces polyamines, which have been shown to enhance wound repair and have been implicated as regulatory factors in immune responses. Our data in two murine models of colitis indicate that supplementation of mice with L-Arg or deletion of iNOS improves colitis, while inhibition of arginase or ODC exacerbates disease. L-Arg uptake into cells is primarily dependent on the cationic amino acid transporter (CAT) proteins, particularly CAT2, which is the predominant transporter in macrophages and CAT1, which is ubiquitously expressed. We will show preliminary data that L-Arg availability is important in cellular functions such as global protein translation, wound repair, and responses to inflammatory stimuli. We will also show that CAT2 expression is upregulated in colitis tissues and colitis-associated tumors, and that mice deficient in CAT2 appear to have exacerbation of colitis. Our hypothesis is that L-Arg availability is an important regulator of mucosal inflammation in IBD such that the amount of L-Arg in the extracellular environment, the transport of L- Arg from outside to inside cells, and the balance of competing metabolic pathways for the utilization of L-Arg are all important in immunomodulation. Our specific aims are to determine the biological effects of L-Arg supplementation and the role of its uptake and metabolism in models in which we will study: 1.) In vitro: A.) epithelial integrity; and B.) macrophage function; 2.) In vivo colitis: A.) clinical parameters; B.) tissue iNOS and polyamine levels, and serum NO and L-Arg levels; C.) biological effects on colonic epithelial cells and macrophages, D.) responses in colonic lymphocytes; 3.) In vivo colitis-associated cancer: A.) clinical parameters; and B.) tumor CAT1, CAT2, iNOS, cytokine, and polyamine levels, and serum NO and L-Arg levels. In these studies, we seek to establish new insights into the role of L-Arg in mucosal immunology and to provide evidence for the potential beneficial effects of L-Arg supplementation in both IBD and IBD-associated cancer while establishing the importance of L-Arg uptake in this process. This work is expected to provide the groundwork for translational studies in patients that could lead to new adjunctive therapies that would be safe, effective, and low in cost and improve the long-term outcome in IBD. PUBLIC HEALTH REVELANCE: Inflammatory bowel disease (IBD) affects more than one million Americans and results in a substantial amount of suffering and the risk for developing cancer of the colon. In this project we will test the hypothesis that supplementation of the amino acid L-arginine (L-Arg) is beneficial in these diseases and that L-Arg uptake into cells has an essential role in the modulation of intestinal inflammation. We will use in vitro and in vivo models of colitis and colitis-associated cancer to conduct mechanistic studies that are designed to generate new insights into the immunobiology of IBD and lay the groundwork for new approaches to attenuate inflammation and associated carcinogenesis.

描述（由申请人提供）：炎症性肠病 (IBD)，由溃疡性结肠炎 (UC) 和克罗恩病 (CD) 组成，是美国人群中广泛发病率和进展为结肠癌风险的根源，其中不止一种百万美国人受到影响。半必需氨基酸 L-精氨酸 (L-Arg) 被吹捧为具有许多潜在益处（包括增强免疫力）的补充剂。为了响应 RFA AT-07-004，我们将在小鼠模型中进行机制研究，以探讨 L-Arg 作为 IBD 补充剂的潜在价值，并确定它是否可以降低结肠炎相关癌症的风险。在免疫激活条件下，L-Arg 利用的两条主要途径是诱导型一氧化氮 (NO) 合酶 (iNOS) 和精氨酸酶途径。精氨酸酶产生 L-鸟氨酸，它是产生多胺的鸟氨酸脱羧酶 (ODC) 的底物，多胺已被证明可以增强伤口修复，并被认为是免疫反应中的调节因子。我们在两种小鼠结肠炎模型中的数据表明，给小鼠补充 L-Arg 或删除 iNOS 可改善结肠炎，而抑制精氨酸酶或 ODC 会加剧疾病。 L-Arg 进入细胞的摄取主要依赖于阳离子氨基酸转运蛋白 (CAT)，特别是 CAT2（巨噬细胞中的主要转运蛋白）和 CAT1（普遍表达）。我们将展示初步数据，表明 L-Arg 的可用性对于细胞功能（例如整体蛋白质翻译、伤口修复和对炎症刺激的反应）很重要。我们还将证明 CAT2 表达在结肠炎组织和结肠炎相关肿瘤中上调，并且缺乏 CAT2 的小鼠似乎会加重结肠炎。我们的假设是，L-Arg 的可用性是 IBD 粘膜炎症的重要调节因子，因此细胞外环境中 L-Arg 的量、L-Arg 从细胞外到细胞内的转运以及竞争性代谢途径的平衡L-Arg 的利用在免疫调节中都很重要。我们的具体目标是确定 L-Arg 补充剂的生物学效应及其在我们将研究的模型中的摄取和代谢的作用：1.) 体外：A.) 上皮完整性； B.) 巨噬细胞功能； 2.) 体内结肠炎：A.) 临床参数； B.) 组织 iNOS 和多胺水平，以及血清 NO 和 L-Arg 水平； C.) 对结肠上皮细胞和巨噬细胞的生物效应，D.) 对结肠淋巴细胞的反应； 3.) 体内结肠炎相关癌症：A.) 临床参数； B.) 肿瘤 CAT1、CAT2、iNOS、细胞因子和多胺水平，以及血清 NO 和 L-Arg 水平。在这些研究中，我们寻求对 L-Arg 在粘膜免疫学中的作用建立新的见解，并为补充 L-Arg 对 IBD 和 IBD 相关癌症的潜在有益作用提供证据，同时确定 L-Arg 的重要性在这个过程中的吸收。这项工作预计将为患者的转化研究奠定基础，从而开发出安全、有效、成本低廉的新辅助疗法，并改善 IBD 的长期结果。 公众健康启示：炎症性肠病 (IBD) 影响超过一百万美国人，导致大量痛苦和患结肠癌的风险。在这个项目中，我们将测试这样的假设：补充氨基酸 L-精氨酸 (L-Arg) 对这些疾病有益，并且细胞摄取 L-Arg 在调节肠道炎症中具有重要作用。我们将使用结肠炎和结肠炎相关癌症的体外和体内模型进行机制研究，旨在产生对 IBD 免疫生物学的新见解，并为减轻炎症和相关致癌作用的新方法奠定基础。