Gut Microbiota and colonic gene expression: A ligran trial in humans

描述（由申请人提供）：结直肠癌（CRC）是美国第三大常见癌症，其发病率在年轻人群中呈上升趋势。饮食是CRC的一个重要危险因素，并且饮食成分被肠道微生物作用改变。高纤维食品中的膳食纤维和植物木脂素的微生物发酵产生生物活性终产物，如丁酸盐和肠木脂素。在一些流行病学研究中，肠木脂素、肠内酯（ENL）和肠二醇（END）与较低的CRC相关。木脂素和膳食纤维已被证明可以减少动物模型中的结肠肿瘤，丁酸盐和END和ENL影响体外癌症风险的重要细胞途径。 我们建议在70名健康男性和女性中进行3个阶段的随机交叉干预（年龄20-45），目的是测试亚麻籽木酚素补充剂和脱脂亚麻籽粉的效果（含有木脂素+膳食纤维）与安慰剂相比：1）来自结肠活组织检查的上皮细胞和基质细胞以及从粪便提取的脱落的结肠细胞中的宿主基因表达; 2）肠道微生物群落组成，和3）肠道微生物组、肠木脂素暴露和结肠基因表达在高和低ENL排泄物中的相互作用。将在三个60天周期的每个周期结束时收集结肠活检、粪便和尿液，以评价木酚素治疗的效果。我们将使用RNA-seq的创新应用程序来测量来自活检和粪便的人类结肠细胞中的基因表达。将使用焦磷酸测序和16 S rRNA基因的QPCR表征肠道微生物组。将通过GC-MS测量尿液中的木脂素。此外，使用来自低和高ENL排泄者的干预参与者子集的样本，我们将测量体外肠道微生物组的功能宏基因组学。 这个拟议的项目将是第一个整合和表征，通过一个独特的跨学科合作，木脂素暴露，肠道微生物生态学和细胞信号传导途径中的基因表达之间的关系。这种安慰剂对照干预的结果将弥合临床前动物模型和流行病学研究的现有知识，并将有助于为CRC预防提供信息。

DESCRIPTION (provided by applicant): Colorectal (CRC) cancer is the third most common cancer in the United States and its incidence is rising in younger populations. Diet is an important risk factor for CRC and dietary constituents are modified by gut microbial action. Microbial fermentation of dietary fiber and plant lignans in high-fiber foods produces bioactive endproducts, such as butyrate and enterolignans. The enterolignans, enterolactone (ENL) and enterodiol (END) have been associated with lower CRC in some epidemiologic studies. Lignans and dietary fiber have been shown to reduce colon tumors in animal models and butyrate and END and ENL influence cellular pathways important to cancer risk in vitro. We propose a 3-period randomized, cross-over intervention in 70 healthy men and women (ages 20-45) with the goal to test the effect of a flaxseed lignan supplement and defatted flaxseed meal (containing lignans + dietary fiber) as compared to placebo on: 1) host gene expression in epithelial and stromal cells from colon biopsies and exfoliated colonocytes extracted from feces; 2) gut microbial community composition, and 3) the interaction of the gut microbiome, enterolignan exposure, and colonic gene expression in high- and low-ENL excreters. Colon biopsies, stool, and urine will be collected at the end of each of the three 60-day periods to evaluate effects of the lignan treatments. We will use an innovative application of RNA-seq to measure gene expression in human colon cells from biopsy and stool. The gut microbiome will be characterized using pyrosequencing and QPCR of the 16S rRNA gene. Lignans will be measured in urine by GC-MS. Further, using samples from a subset of intervention participants who are low-and high-ENL excreters, we will measure the functional metagenomics of the gut microbiome in vitro. This proposed project will be the first to integrate and characterize, through a unique interdisciplinary collaboration, the relationships between lignan exposure, gut microbial ecology, and gene expression in cell- signaling pathways. Results of this placebo-controlled intervention will bridge the current knowledge from pre-clinical animal models and epidemiologic studies and will help to inform approaches for CRC prevention.