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。饮食是结直肠癌的重要危险因素，肠道微生物的作用改变了饮食成分。高纤维食品中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，如丁酸盐和肠脂素。肠内酯、肠内酯（ENL）和肠二醇（END）在一些流行病学研究中与较低的结直肠癌有关。在动物模型中，木脂素和膳食纤维已被证明可以减少结肠肿瘤，而丁酸盐、END和ENL在体外影响对癌症风险重要的细胞通路。我们在70名健康男性和女性（年龄在20-45岁）中进行了一项为期3期的随机交叉干预，目的是测试亚麻籽木脂素补充剂和脱脂亚麻籽粕（含木脂素+膳食纤维）与安慰剂相比对以下方面的影响：1)结肠活检中上皮细胞和基质细胞中的宿主基因表达以及从粪便中提取的脱落结肠细胞；2)肠道微生物群落组成；3)肠道微生物组、肠脂素暴露和高、低enl排泄物中结肠基因表达的相互作用。在三个60天的周期结束时，收集结肠活检、粪便和尿液，以评估木脂素治疗的效果。我们将使用RNA-seq的创新应用来测量活检和粪便中人类结肠细胞的基因表达。肠道微生物组将使用焦磷酸测序和16S rRNA基因的QPCR进行表征。用气相色谱-质谱法测定尿中的木脂素。此外，使用来自低和高enl排泄者的干预参与者子集的样本，我们将在体外测量肠道微生物组的功能宏基因组学。本项目将通过独特的跨学科合作，首次整合和表征木脂素暴露、肠道微生物生态和细胞信号通路中基因表达之间的关系。这项安慰剂对照干预的结果将连接临床前动物模型和流行病学研究的现有知识，并将有助于为预防结直肠癌的方法提供信息。

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.