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: 8690770
• 负责人: Keith T. Wilson
• 金额: $ 37.83万
• 依托单位: VANDERBILT UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-07-01 至 2018-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8690770
• 关键词: Affect; American; Amino Acids; Animals; Apoptosis; Arginine; Award; Azoxymethane; Bone Marrow; Carcinoma; Cationic Amino Acid Transporter 2; Cell Line; Cell physiology; Chimera organism; Citrulline; Clinical; Colitis; Colon; Colon Carcinoma; Colonic Neoplasms; Complementary and alternative medicine; Crohn' s disease; DNA Damage; Defect; Development; Disease; Disease remission; Down-Regulation; Dysplasia; Enzymes; Epithelial; Epithelial Cells; Exhibits; Funding; Gene Expression; Histology; Human; Immune response; Immunotherapy; In Vitro; Inflammation; Inflammatory Bowel Diseases; Injury; Intervention; Investigation; Lymphocyte; Macronutrients Nutrition; Maintenance; Malignant Neoplasms; Metabolism; Modeling; Morbidity - disease rate; Mus; Myelogenous; NOS2A gene; National Center for Complementary and Alternative Medicine; Natural Immunity; Nitric Oxide; Oral; Ornithine; Ornithine Decarboxylase; Ornithine-oxo-acid aminotransferase; Pathway interactions; Patients; Permeability; Phenotype; Polyamines; Process; Production; Proline; Protein Biosynthesis; Regulatory T-Lymphocyte; Reporting; Risk; Role; Sodium Dextran Sulfate; Source; Splenocyte; Supplementation; Tissues; Tumor Tissue; Ulcerative Colitis; Work; Wound Healing; adaptive immunity; arginase; base; cytokine; disorder prevention; human NOS2A protein; human study; immune function; improved; inhibitor/antagonist; injury and repair; innate immune function; macrophage; migration; prevent; public health relevance; response; semi essential amino acid; treatment strategy; tumor; tumorigenesis; uptake

DESCRIPTION (provided by applicant): Inflammatory bowel disease (IBD), consisting of ulcerative colitis (UC) and Crohn's disease, is a source of substantial morbidity for 1.4 million people affected in the USA, and it can progress to colon cancer. It is difficult to treat, with cosly immunotherapies only inducing remission in less than half of cases. We have been focusing on the role of the semi-essential amino acid, L-arginine (L-Arg) as a complementary and alternative medicine. We have demonstrated mechanisms for beneficial effects of L-Arg in vitro and in colitis. Cationic amino acid transporter 2 (CAT2), the inducible transporter of L-Arg, and uptake of L-Arg are upregulated in murine colitis, and oral L-Arg supplementation is effective as a treatment for epithelial injury and inflammation induced by dextran sulfate sodium (DSS), a model that mimics UC. CAT2 expression, L-Arg uptake, and L-Arg levels are all decreased in UC tissues. CAT2-/- mice exhibit marked exacerbation of DSS colitis, and colon tumorigenesis in the azoxymethane (AOM)-DSS model of colitis-associated carcinoma (CAC). CAT2-/- mice do not respond to L-Arg supplementation in the DSS colitis model, suggesting that L-Arg alone as a therapy for human UC may not be sufficient to overcome its impaired transport into tissues. Colonic epithelial restitution in a wound repair model is dependent on CAT2 and this is due to utilization of L-Arg by arginase that generates L-ornithine (L-Orn), which can be metabolized by either ornithine decarboxylase (ODC) to generate polyamines, or ornithine aminotransferase (OAT) to generate L-proline (L-Pro). While inhibition of arginase or knockdown of arginase 1 (Arg1) prevented restitution, this could be completely restored, in the presence of L- Arg, when either L-Orn or L-Pro was added. Knockdown of OAT, but not ODC, prevented beneficial effects of L-Arg on restitution, implicating OAT in the maintenance of epithelial function. Additionally, ODC+/- mice exhibit improvement in DSS colitis, with increased tissue macrophage NO production, and enhanced regulatory T cell and macrophage responses, indicating a deleterious role for polyamines in this model. We hypothesize that benefits of L-Arg in colitis and colitis-associated tumorigenesis depend on CAT2 and downstream effectors to improve epithelial restitution, innate immune function, and adaptive immunity. In our Specific Aims we will determine if: 1) exacerbation of DSS colitis due to deletion of CAT2 and loss of L-Arg availability that mimics human UC is due to an epithelial or macrophage defect and if this is ameliorated by supplementation of L-Orn or L-Pro in combination with L-Arg; 2.) improvement in DSS colitis in ODC+/- mice is due to an epithelial or macrophage effect and if it results from enhanced L-Arg availability for iNOS and/or OAT; 3.) accelerated tumorigenesis with CAT2 deletion is due to an epithelial or macrophage defect and if this process can be beneficially modulated by downregulation of ODC or supplementation of L-Orn or L-Pro in combination with L- Arg. Through investigation of epithelial and immune function, these studies seek to provide new macronutrient- based strategies for treatment of IBD and prevention of colitis-associated dysplasia and carcinoma.

描述（由申请人提供）：炎症性肠病 (IBD)，由溃疡性结肠炎 (UC) 和克罗恩病组成，是美国 140 万人患病的主要原因，并且可以进展为结肠癌。它很难治疗，昂贵的免疫疗法只能使不到一半的病例得到缓解。我们一直关注半必需氨基酸 L-精氨酸 (L-Arg) 作为补充和替代药物的作用。我们已经证明了 L-Arg 在体外和结肠炎中的有益作用机制。阳离子氨基酸转运蛋白 2 (CAT2)（L-Arg 的诱导转运蛋白）和 L-Arg 的摄取在小鼠结肠炎中上调，口服 L-Arg 补充剂可有效治疗右旋糖酐硫酸钠引起的上皮损伤和炎症(DSS)，一个模仿 UC 的模型。 UC 组织中 CAT2 表达、L-Arg 摄取和 L-Arg 水平均降低。 CAT2-/- 小鼠在结肠炎相关癌 (CAC) 的氧化偶氮甲烷 (AOM)-DSS 模型中表现出 DSS 结肠炎和结肠肿瘤发生的显着恶化。在 DSS 结肠炎模型中，CAT2-/- 小鼠对补充 L-Arg 没有反应，这表明单独使用 L-Arg 作为人类 UC 的疗法可能不足以克服其向组织转运受损的情况。伤口修复模型中的结肠上皮恢复依赖于 CAT2，这是由于精氨酸酶利用 L-Arg 产生 L-鸟氨酸 (L-Orn)，L-鸟氨酸可以被鸟氨酸脱羧酶 (ODC) 代谢产生多胺，或鸟氨酸转氨酶 (OAT) 生成 L-脯氨酸 (L-Pro)。虽然精氨酸酶的抑制或精氨酸酶 1 (Arg1) 的敲除会阻止恢复，但在 L-Arg 存在的情况下，当添加 L-Orn 或 L-Pro 时，这种情况可以完全恢复。 OAT 的敲低（而非 ODC）阻止了 L-Arg 对恢复的有益作用，这表明 OAT 参与了上皮功能的维持。此外，ODC+/- 小鼠的 DSS 结肠炎有所改善，组织巨噬细胞 NO 产生增加，调节性 T 细胞和巨噬细胞反应增强，表明多胺在该模型中具有有害作用。我们假设 L-Arg 在结肠炎和结肠炎相关肿瘤发生中的益处依赖于 CAT2 和下游效应子来改善上皮恢复、先天免疫功能和适应性免疫。在我们的具体目标中，我们将确定是否：1) 由于 CAT2 删除和 L-Arg 可用性丧失而导致 DSS 结肠炎恶化 模拟人类 UC 的原因是上皮细胞或巨噬细胞缺陷，如果通过补充 L-Orn 或 L-Pro 与 L-Arg 组合可以改善这种情况； 2.) ODC+/-小鼠中DSS结肠炎的改善是由于上皮细胞或巨噬细胞的作用，并且是由于iNOS和/或OAT的L-Arg可用性增强所致； 3.) CAT2 缺失加速肿瘤发生是由于上皮细胞或巨噬细胞缺陷所致，并且是否可以通过下调 ODC 或补充 L-Orn 或 L-Pro 与 L-Arg 组合来有益地调节该过程。通过对上皮和免疫功能的研究，这些研究旨在提供新的基于常量营养素的策略，用于治疗 IBD 和预防结肠炎相关的发育不良和癌症。