Intestinal Microbiota, Diet and Risk of Colorectal Adenomas

描述（由申请人提供）：来自动物和人类研究的证据表明，肠道细菌可能有助于结直肠癌（CRC）的发病机制，CRC是美国癌症死亡率的主要主要原因。肠道微生物群与CRC之间联系的潜在机制是通过饮食和炎症。我们提出了一个模型，肠道细菌通过饮食，炎症和代谢的外源性物质在CRC的病因学中发挥了重要作用。我们建议测试粘附细菌（粘附）与结直肠腺瘤风险升高有关的假设，以及这些细菌调节饮食，炎症和结直肠腺瘤之间的关联。我们认为，不同的模式，直肠定植或存在/不存在特定的细菌物种将与腺瘤的风险。具体目标是：1）确定是否遵守（粘膜相关）细菌群落组成和结构2）评估粘附细菌谱与全身或局部炎症标志物的相关性，（IL-12、IL-23、IL-4、IL-17、INF α、IL-8、IL-10和TGF-β;巨噬细胞、NK细胞、T细胞-CD 4+和CD 8 +;在有和没有腺瘤的受试者中NF-（B（p65）和STAT 3）的蛋白表达，3）评估粘附细菌谱与饮食/生活方式之间的关联，如纤维、肉类摄入、肥胖（体重指数（BMI）、腰臀比）和与结直肠腺瘤相关的NSAID使用。对人类肠道细菌多样性与疾病的关系的评估在一定程度上受到限制，因为这些生物体在培养中很难生长。分子方法的最新进展使评估肠道微生物群在结肠癌等疾病中的作用成为可能。为了验证我们的假设，我们建议使用基于高度保守的16 S细菌rRNA基因的分子系统发育方法来评估肠道微生物群对结直肠腺瘤发展的贡献。这些方法包括16 S rRNA基因的PCR扩增、末端限制性片段长度多态性（TRFLP）、细菌克隆文库的产生和测序。本研究将使用从600例患者（300例病例和300例对照）中获得的结肠活检标本和风险因素数据，如来自一项正在进行的结直肠腺瘤研究（饮食与健康研究）（NCI R 01 CA 44684）的饮食和炎症。关于肠道细菌在腺瘤发展中的作用的信息有限。这项研究将为微生物群的组成和多样性及其与结直肠腺瘤和已知风险因素的关联提供重要见解。这项研究的发现可能会导致开发策略来操纵肠道微生物群，以预防结直肠腺瘤和癌症，并识别高风险个体。公共卫生相关性：本研究的目的是评估大肠内壁细菌群落的组成和结构，与结直肠腺瘤和已知的风险因素（如饮食和炎症）有关。这项研究的结果可以帮助识别腺瘤高风险的个体，并促进控制肠道微生物群以预防结直肠腺瘤和癌症的策略的发展。

DESCRIPTION (provided by applicant): Evidence from animal and human studies suggests that intestinal bacteria may contribute to the pathogenesis of colorectal cancer (CRC), a major leading cause of cancer mortality in the United States. Potential mechanisms for the link between gut microbiota and CRC is through diet and inflammation. We propose a model whereby intestinal bacteria play a prominent role in the etiology of CRC through diet, inflammation and metabolism of xenobiotics. We propose to test the hypothesis that adherent bacteria (adherent) are linked with elevated risk of colorectal adenoma and that these bacteria modulate the association between diet, inflammation and colorectal adenomas. We propose that distinct patterns of commensal colonization or presence/absence of specific bacteria species will correlate with adenoma risk. The specific aims are to 1) determine whether the adherent (mucosa-associated) bacteria community composition and structure (profiles) differ between subjects with adenomas and those without adenomas, 2) evaluate the associations of adherent bacteria profiles and systemic or local markers of inflammation (IL-12, IL-23, IL-4, IL-17, INF(, IL-8, IL-10 and TGF-(; macrophages, NK cells, T cells- CD4+ and CD8+; protein expression of NF-(B (p65) and STAT3) among subjects with and without adenomas, 3) assess the association between adherent bacteria profiles and diet/lifestyle such as fiber, meat intake, obesity (body mass index (BMI), waist-hip-ratio), and NSAID use in relation to colorectal adenomas. Evaluation of the diversity of gut bacteria in relation to disease in humans is limited in part, by the difficulty growing these organisms in culture. Recent advances in molecular methods have made it possible to assess the role of intestinal microbiota in diseases such as colon cancer. To test our hypothesis, we propose to use molecular-phylogenetic methods based on the highly conserved 16S bacteria rRNA gene to assess the contribution of intestinal microbiota to the development of colorectal adenomas. These methods include PCR amplification of the 16S rRNA gene, terminal restriction fragment length polymorphism (TRFLP), generation of bacteria clone libraries and sequencing. This study will use colonic biopsy specimens obtained from 600 patients (300 cases and 300 controls) and risk factor data such as diet and inflammation from a funded ongoing study of colorectal adenomas, the Diet and Health Study (NCI R01 CA 44684). Limited information exists on the role of gut bacteria in the development of adenomas. This study will provide critical insights on the composition and diversity of the microbiota and their association with colorectal adenomas and known risk factors. The findings from this study could lead to the development of strategies to manipulate the intestinal microbiota to prevent colorectal adenomas and cancer as well as identify individuals at high risk. PUBLIC HEALTH RELEVANCE: The goal of this study is to evaluate the composition and structure of bacteria communities that reside on the lining of the large bowel, in relation to colorectal adenomas and known risk factors such as diet and inflammation. The findings from this study could help identify individuals at high risk of adenomas as well as enhance the development of strategies to manipulate the intestinal microbiota to prevent colorectal adenomas and cancer