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

总结： 炎症性肠病（IBD）困扰着美国超过300万人，在世界范围内正在增加， 导致结肠炎相关致癌作用（CAC）。我们正在寻找新的安全的IBD治疗方法， 有效且廉价，也可以降低CAC的风险。亚精胺（Spd）是一种多胺， 腐胺和来自精胺氧化酶（SMOX）对精胺的反转化。最近的高影响力研究 已经表明，补充亚精胺可以改善心血管健康、长寿和老年生活质量， 不会增加患癌症的风险。Spd已成功用于I期临床试验。我们有 开发了一种灵敏，准确的基于质谱的多胺检测方法，提高了 我们在这个项目上的能力。我们最近的发现支持使用Spd作为结肠炎的新策略 治疗和CAC预防。长期目标是进一步阐明其范围和机制 Spd的保护作用，以获得未来IBD人体临床试验所需的见解。我们建议的研究 我们的数据表明：1）SMOX（Spd的关键来源）的表达在患者中减少 溃疡性结肠炎（UC）和相关的发育不良。2)Smox缺失的小鼠结肠中Spd减少 以及葡聚糖硫酸钠（DSS）结肠炎（一种具有UC特征的模型）和CAC的恶化。 氧化偶氮甲烷（AOM）-DSS模型。3)补充Spd可恢复结肠Spd水平并预防结肠炎 和CAC。4)Spd是生成羟腐胺赖氨酸的底物，羟腐胺赖氨酸是由脱氧羟腐胺赖氨酸合成酶产生的氨基酸 （DHPS），这是一种高度特异性的蛋白质翻译形式所必需的，hypusination，涉及激活 真核生物翻译起始因子5A（EIF 5A）和羟腐胺赖氨酸化的EIF 5A（EIF 5AHyp）的形成。DHPS水平 在UC患者中是低的。EIF 5AHyp在DSS结肠炎和AOM期间通过Smox缺失减少并通过Spd恢复- DSS诱导的CAC，调节巨噬细胞功能，并增强结肠上皮恢复。5)亲电体， 如左甘定（LGs），是脂质过氧化的破坏性产物，可导致免疫功能障碍 与蛋白质和DNA形成加合物和肿瘤风险;我们发现在人类UC中加合物增加， CAC和亲电体的特异性清除剂减少AOM-DSS中的加合物形成和致癌作用 模型重要的是，我们证明了Spd可以抑制LG。我们假设亚精胺的潜在益处 在结肠炎和癌变中的作用是由于对免疫反应、上皮功能、羟腐胺酸作用和 亲电体清除我们的目的是：1）确定保护的分子和细胞机制， Spd在急性和慢性结肠炎模型和CAC中的作用，包括对转录组/代谢组，自噬， 和免疫细胞对上皮细胞功能的研究。 2)为了确定Spd是否通过hypusination起作用，使用具有上皮或骨髓特异性Dhps缺失的小鼠。 3)为了确定Spd作为亲电清除剂在减少炎症、基因组不稳定性和 肿瘤发生我们期望为IBD的结肠炎治疗和CAC预防提供新的策略。

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.