Identifying the active factor of an anti-inflammatory chemopreventive bacterium

鉴定抗炎化学预防细菌的活性因子

• 批准号: 10600457
• 负责人: Jimmy W Crott
• 金额: $ 23.59万
• 依托单位: BOSTON UNIVERSITY MEDICAL CAMPUS
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-05-01 至 2024-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10600457
• 关键词: Identifying; active; factor; anti; inflammatory

Project Abstract/Summary Colorectal cancer (CRC) remains a major public health issue, with approximately 145,000 new cases and 51,000 deaths from this disease per year in the US alone. Alterations in the composition of the gut microbiota and elevated inflammation are established risk factors for CRC. We made the novel observation that the normal gut bacterium Parabacteroides distasonis (Pd) suppresses colorectal inflammation and tumor formation in mice. Importantly, we show that Pd suppresses the activation of the pro-inflammatory, pro-tumorigenic TLR4 signaling pathway. The objectives of this application are to determine whether blocking TLR4 is required for the ant-tumor effects of Pd, to identify the active factor of Pd and its host target and finally to define how Pd influences immune cell populations in the colon. Based on our robust data, we hypothesize that the chemopreventive effect of Pd is achieved by the suppression of pro-inflammatory TLR4 signaling and the recruitment of inflammation quelling T regulatory (Treg) cells to the colon. The specific aims of the study are to: 1) To identify anti-inflammatory factor of Pd; 1A) To test whether the anti-TLR4 function of Pd is required for its chemopreventive effect; 1B) To identify the molecular target of the Pd anti-inflammatory molecule and 2) To define how Pd influences immune cell populations in the colonic mucosa. The aims of this study will be addressed by comparing the ability of various closely-related bacterial species to inhibit TLR4 signaling in vitro followed by comparative genomics to identify genes common to inhibitory species but without homologs in non-inhibitory species. The function of candidates will be evaluated by expressing them in E.coli Nissle 1917 (EcN) and mutating them in Pd. To evaluate whether TLR4 inhibition is required for chemoprevention by Pd we will compare the ability of Pd and Pd lacking anti-TLR4 function to suppress colon tumorigenesis with EcN and EcN expressing Pd anti-TLR4 genes. Host target proteins will be identified by co-immunoprecipitation with the recombinant tagged Pd protein. Finally, the influence of Pd on colonic immune cells will be evaluated by comparing specific cancer and microbiota relevant immune cell populations between Pd fed and control mice over time. Understanding Pd’s mechanism of action and identifying its active and target molecules will pave the way for this bacterium, or its active component, to be utilized in the prevention of CRC. Our long-term goal is to identify bacteria with chemopreventive properties and to understand their mechanisms of action. Importantly, Pd appears to be compatible with other microbial therapies and does not disrupt the resident microbiota. These studies are highly worthwhile because although a few agents show promise as chemopreventive agents in pre-clinical studies, aspirin (a drug developed over 100 years ago) remains the only agent for which we have compelling evidence of efficacy and its detrimental effects may outweigh those benefits. These studies directly address the mission of the NCI to develop the knowledge base that will lessen the burden of cancer in the United States and around the world.

项目摘要/总结 结直肠癌 (CRC) 仍然是一个主要的公共卫生问题，约有 145,000 例新病例和 51,000 例 仅在美国每年就有因这种疾病死亡的人数。 炎症升高是结直肠癌的既定危险因素我们进行了新的观察，即正常肠道。 细菌 Parabacteroides distasonis (Pd) 可抑制小鼠结直肠炎症和肿瘤形成。 重要的是，我们发现 Pd 抑制促炎、促肿瘤 TLR4 信号传导的激活 本申请的目的是确定抗肿瘤是否需要阻断 TLR4。 Pd 的作用，确定 Pd 的活性因子及其宿主靶点，并最终确定 Pd 如何影响免疫 根据我们可靠的数据，我们认为 Pd 的化学预防作用是 通过抑制促炎 TLR4 信号传导和招募炎症平息 T 来实现 该研究的具体目的是： 1) 鉴定结肠的抗炎因子。 Pd；1A) 测试Pd的抗TLR4功能是否是其化学预防作用所必需的；1B) 确定 Pd 抗炎分子的分子靶点以及 2) 定义 Pd 如何影响免疫细胞 本研究的目的将通过比较不同群体的能力来实现。 密切相关的细菌物种在体外抑制 TLR4 信号传导，然后通过比较基因组学来识别 抑制性物种共有的基因，但非抑制性物种中没有同源基因 候选基因的功能。 将通过在大肠杆菌 Nissle 1917 (EcN) 中表达它们并在 Pd 中突变它们来评估是否。 TLR4 抑制是 Pd 化学预防所必需的，我们将比较 Pd 和缺乏抗 TLR4 的 Pd 的能力 EcN 和表达 Pd 抗 TLR4 基因的 EcN 具有抑制结肠肿瘤发生的功能。 将通过与重组标记的Pd蛋白进行免疫共沉淀来鉴定最后，Pd的影响。 将通过比较特定癌症和微生物群相关免疫细胞来评估对结肠免疫细胞的影响 随着时间的推移，Pd 喂养小鼠和对照小鼠之间的种群数量了解 Pd 的作用机制并识别。 其活性分子和目标分子将为该细菌或其活性成分在 我们的长期目标是识别具有化学预防特性的细菌并了解它们。 重要的是，Pd 似乎与其他微生物疗法兼容，而且确实如此。 不会破坏常驻微生物群，这些研究非常有价值，因为尽管一些药物表明。 阿司匹林（一种 100 多年前开发的药物）在临床前研究中有望成为化学预防剂 仍然是我们拥有令人信服的功效证据的唯一药物，其有害影响可能 这些研究直接解决了 NCI 开发知识库的使命。 这将减轻美国和世界各地的癌症负担。