Spermidine as a New Therapy for Colitis and Chemopreventive for Colitis-associated Carcinogenesis

摘要： 炎症性肠病(IBD)在美国困扰着300多万人，在全球范围内正在增加，而且 导致结肠炎相关癌变(CAC)。我们正在寻找安全的新的IBD辅助疗法， 有效且廉价，这也可以降低CAC的风险。亚精胺(Spd)是一种多胺，由 腐胺和精胺氧化酶(SMOX)对精胺的反向转化。最近的高影响力研究 已表明补充SPD可改善心血管健康、寿命和老年生活质量，以及 不会增加患癌症的风险。Spd已成功应用于I期临床试验。我们有 开发了一种灵敏、准确的基于质谱学的多胺检测方法，该方法已经增强了 我们在这个项目上的能力。我们最近的发现支持使用SPD作为治疗结肠炎的新策略 治疗和预防CAC。长期目标是进一步阐明潜在的范围和机制 SPD的保护作用，以获得未来人类IBD临床试验所需的见解。我们建议的研究 我们的数据表明：1)SPD的一个关键来源SMOX的表达在患者中减少 伴有溃疡性结肠炎(UC)和伴随的异型增生。2)Smox缺失的小鼠结肠SPD减少 以及具有UC特征的葡聚糖硫酸钠(DSS)结肠炎和CAC的恶化。 AOM-DSS模型。补充Spd可恢复结肠Spd水平并预防结肠炎 和CAC。4)Spd是脱氧亚硫氨酸合成酶产生亚精氨酸的底物。 (Dhps)，这是一种高度特异的蛋白质翻译所需的形式，激活，涉及激活 真核细胞翻译起始因子5A(EIF5A)及其亚基的形成。脱氢表雄酮水平 在UC患者中水平较低。在DSS结肠炎和AOM中，EIF5AHyp通过Smox缺失而减少，并由SPD恢复- DSS诱导CAC，调节巨噬细胞功能，促进结肠上皮修复。5)亲电性； 如左旋糖苷(LGs)，是脂质过氧化的破坏性产物，可导致免疫功能障碍 和肿瘤风险通过与蛋白质和DNA形成加合物；我们发现在人类UC和 CAC和一种特殊的亲电体清除剂减少AOM-DSS中加合物的形成和致癌作用 模特。重要的是，我们证明了SPD可以清除LGs。我们假设SPD的潜在好处 在结肠炎和癌变中的作用是由于对免疫反应、上皮功能、激素化和 电泳液清道夫。我们的目标是：1)确定保护的分子和细胞机制 SPD在急、慢性结肠炎模型和CAC中的作用，包括对转录组/代谢组、自噬、 以及使用细胞特异性表达人SMOX的转基因小鼠的免疫细胞与上皮细胞功能。 2)利用上皮或髓系特异性DHPs缺失的小鼠，确定SPD是否通过下丘脑起作用。 3)确定Spd作为一种电泳体清除剂在减少炎症、基因组不稳定和 肿瘤发生学。我们希望为IBD的结肠炎治疗和CAC预防提供一种新的策略。

SUMMARY: Inflammatory bowel disease (IBD) afflicts over three million people in the USA, is increasing worldwide, and leads to colitis-associated carcinogenesis (CAC). We are seeking new adjunctive IBD therapies that are safe, effective, and inexpensive that could also reduce risk for CAC. Spermidine (Spd) is a polyamine generated from putrescine and from back-conversion of spermine by spermine oxidase (SMOX). Recent high-impact studies have shown that Spd supplementation improves cardiovascular health, longevity and quality of life in aging, and does not increase the risk for cancer. Spd has been used successfully in Phase I clinical trials. We have developed a sensitive, accurate mass spectrometry-based assay for polyamine detection, which has enhanced our capabilities for this project. Our recent discoveries support the use of Spd as a new strategy for colitis treatment and CAC prevention. The long-term goal is to further elucidate the scope and mechanisms underlying the protective effect of Spd to gain insights needed for future human clinical trials in IBD. Our proposed studies are supported by our data indicating that: 1) Expression of SMOX, a key source of Spd, is reduced in patients with ulcerative colitis (UC) and associated dysplasia. 2) Mice with Smox deletion have reduced Spd in the colon and exacerbation of both dextran sulfate sodium (DSS) colitis, a model with features of UC, and CAC in the azoxymethane (AOM)-DSS model. 3) Spd supplementation restores colon Spd levels and protects against colitis and CAC. 4) Spd is the substrate for generation of hypusine, an amino acid produced by deoxyhypusine synthase (DHPS), which is required for a highly specific form of protein translation, hypusination, involving activation of eukaryotic translation initiation factor 5A (EIF5A) and formation of hypusinated EIF5A (EIF5AHyp). DHPS levels are low in UC patients. EIF5AHyp is reduced by Smox deletion and restored by Spd during DSS colitis and AOM- DSS-induced CAC, regulates macrophage function, and enhances colonic epithelial restitution. 5) Electrophiles, such as levuglandins (LGs), are damaging products of lipid peroxidation that can lead to immune dysfunction and neoplastic risk by forming adducts with proteins and DNA; we found increased adducts in human UC and CAC, and a specific scavenger of electrophiles reduced adduct formation and carcinogenesis in the AOM-DSS model. Importantly, we demonstrate that Spd can scavenge LGs. We hypothesize that potential benefits of Spd in colitis and carcinogenesis are due to effects on immune responses, epithelial function, hypusination, and electrophile scavenging. Our Aims are: 1) To determine the molecular and cellular mechanisms of protection by Spd in acute and chronic colitis models and CAC, including effects on the transcriptome/metabolome, autophagy, and immune cell versus epithelial cell function using transgenic mice with cell-specific human SMOX expression. 2) To determine if Spd acts through hypusination, using mice with epithelial- or myeloid-specific deletion of Dhps. 3) To determine the role of Spd as an electrophile scavenger in reducing inflammation, genomic instability, and tumorigenesis. We expect to deliver a new strategy for colitis treatment in IBD and for CAC prevention.