Effects of inflammaging on intestinal epithelial cells and aspirin chemoprevention.

项目摘要 先前的随机对照试验S表明，小剂量阿司匹林(81-100毫克/天)可减少 结直肠癌(CRC)的风险。美国预防服务工作组(USPSTF)建议LDA 在50-59岁的成年人中预防CRC。然而，最近对19,114名老年人(65岁)进行的随机对照研究报告称， 晚年开始LDA对结直肠癌的发病率没有好处，对死亡率有潜在的不利影响。因为 结直肠癌的发病率随着年龄的增长而上升，了解衰老对老年人的关系和功能影响 LDA的化学预防作用是一个高度优先的问题。我们的工作模型是LDA对结肠的影响 老年人由于年龄相关的肠道干细胞(ISC)数量和继发功能的变化而有所不同 更高的基础炎症基调，也就是。“激情四射”。正常情况下，CRC似乎主要是 由Lgr5 ISCs和阿司匹林样非类固醇抗炎药的致癌突变驱动似乎优先消除 癌前LGR5-ISCs。然而，我们的初步数据表明，老年小鼠(20-22个月[MOS])，如 与幼鼠(2-3个月)相比，小鼠的小肠Lgr5 ISCs较少，再生能力较差，这也是 在APC肿瘤抑制模型中致瘤性较低。尽管如此，像人类一样，衰老的小鼠也会自发地 发生更多的肿瘤，表明非Lgr5细胞也是肠癌的起源 这些细胞对LDA的敏感性较低。LDA调节前列腺素(PG)水平，包括 PGE2。我们还发现PGE2通过其受体Ptger4影响ISC的功能，这种信号转导可以驱动ISCs 进入类似胎儿的状态(Hopx)，这是由河马/YAP信号介导的。因此，在火化的背景下， 升高的PGE2可能不可逆转地损害结肠(CISC)池，导致体内代偿功能 选择促进肿瘤发生的cISCs。通过我们的双盲、安慰剂对照RCT，我们展示了 调节PG音调和抑制PG合成是阿司匹林作用模式的核心。我们的中央 假设是衰老和与年龄相关的过程促进了CISC池(Lgr5 CISCs)的减少，即 通常对阿司匹林化学预防敏感。我们认为，在生命早期开始LDA可以预防 这种与年龄相关、炎症相关和/或PGE2介导的对CISC池的损害。相比之下，在 随着年龄的增长，可能会出现“不归路点”，在这种情况下，LDA的启动不再对年龄具有保护作用。 相关的变化，在中央情报局的池。在这项提案中，我们将扩展我们现有的RCT，以检查 单细胞分辨率下的结肠上皮LDA，患者衍生的有机物质，以及老年人的尿PGs。 我们将使用新的体内临床前模型来分析炎症对PG信号转导和LDA的作用。 CISCs。然后，我们将研究这些途径对结肠癌发生和发展的因果关系。这些 研究可能会为意外发现LDA对老年人的不同影响提供生物学解释， 这可能会影响临床指南或生物标记物的开发，以优化LDA的风险-收益概况。

PROJECT ABSTRACT Previous randomized controlled trials (RCT)s demonstrate that low-dose aspirin (LDA, 81-100mg/day) reduces the risk of colorectal cancer (CRC). The U.S. Preventive Services Task Force (USPSTF) recommends LDA to prevent CRC in adults aged 50-59. However, a recent RCT among 19,114 older (65+) individuals reported that initiating LDA late in life had no benefit on CRC incidence and was potentially detrimental for mortality. Because CRC incidence rises with age, understanding the relationship and functional impact of aging on the chemopreventive effects of LDA is a high priority. Our working model is that the effect of LDA on the colon differs in older individuals due to age-related changes in intestinal stem cell (ISC) number and function secondary to a process of higher basal inflammatory tone, a.k.a. “inflammaging”. Normally, CRC appears to be primarily driven by oncogenic mutations in Lgr5+ ISCs and aspirin-like NSAIDs appear to preferentially eliminate premalignant Lgr5+ ISCs. However, our preliminary data demonstrates that old mice (20-22 months [mos]), as compared to young mice (2-3 mos), have fewer, less regenerative small intestinal Lgr5+ ISCs, which are also less tumorigenic in an Apc tumor suppressor model. Nonetheless, like humans, aged mice spontaneously develop a greater number of tumors, indicating that non-Lgr5+ cells are also the origin of intestinal cancers in aged mice and that these cells are less sensitive to LDA. LDA modulates prostaglandin (PG) levels, including PGE2. We also find that PGE2 impacts ISC function through its receptor Ptger4 and this signaling can drive ISCs into a fetal-like state (Hopx+) that is mediated by Hippo/Yap signaling. Thus, in the setting of inflammaging, elevated PGE2 may irreversibly compromise the colon (cISC) pool leading to compensatory functions within select cISCs that promote tumorigenesis. Through our double-blind, placebo-controlled RCT, we demonstrated that modulation of PG tone and inhibition of PG synthesis is central to aspirin’s mode of action. Our central hypothesis is that aging and age-related processes promote a decrease in the cISC pool (Lgr5+ cISCs) that is normally sensitive to aspirin chemoprevention. We propose that initiation of LDA earlier in life protects against this age-related, inflammation-associated, and/or PGE2-mediated damage to the cISC pool. In contrast, with advancing age there may be a “point-of-no-return” in which initiation of LDA is no longer protective against age- related changes in the cISC pool. In this proposal, we will expand our existing RCT to examine the impact of LDA on colonic epithelium at single cell resolution, patient-derived organoids, and urinary PGs in older adults. We will use novel in vivo preclinical models to dissect the role of inflammaging on PG signaling and LDA on cISCs. We will then examine the causality of these pathways on colon tumor incidence and progression. These studies may offer a biological explanation for the unexpected finding of a differential effect of LDA in older adults, which may influence clinical guidelines or the development of biomarkers to optimize LDA’s risk-benefit profile.