基于代谢组学和宏蛋白质组学解析溃疡性结肠炎肠道菌群代谢变化及机制

The metabolic disorder of gut microbiota is closely related to the occurrence and development of ulcerative colitis (UC). However, there has been no comprehensive study of the metabolic changes of gut microbiota in UC due to the microbiome complexity. Our preliminary metabolomics study of in-vitro culture showed that gut microbiota of UC patients exhibited altered nutrition utilization, lipid and peptide metabolism, as well as secondary metabolite production with reduced individual diversity. In this proposed study, we aim to study the in vivo metabolic alteration of gut microbiota in UC by parallel fecal metabolomics and metaproteomics with in-depth characterization and annotation of altered gut microbial metabolites. Multiple digestion proteases and fragmentation modes will be employed to increase the analytical depth and sequence coverage of metaproteomics. Different proteomics software and database searching strategies will be integrated to improve the accuracy. The optimized data analysis workflow will be used to study the association between gut microbial metabolome alteration and metaproteome level evidence in terms of community structure, protein abundance and post-translational modifications. This study holds promises for providing a theoretical basis for understanding the pathological mechanism of UC mediated by gut microbiota imbalance and the corresponding targeted therapy of the microbiota.

肠道菌群代谢紊乱与溃疡性结肠炎（UC）的发生发展密切相关，但由于肠道菌群的复杂性，目前依然缺乏对UC状态下肠道菌群代谢变化及其机制的系统性研究。预实验结果显示，UC患者肠道菌群在体外培养条件下的营养利用、脂类和多肽类的代谢及其合成的次级代谢产物均发生显著变化，并且个体代谢差异性减小。我们拟进一步对UC病人和健康人粪便样品进行代谢组学和宏蛋白质组学研究；解析UC病人肠道菌群的体内代谢变化及机制；对变化的肠道菌群代谢物进行系统性鉴定和注释；发展多种蛋白酶酶切和多重质谱碎裂模式提高宏蛋白质组的分析深度和序列覆盖度；开发对比不同搜库引擎、搜库策略和质控方法提升宏蛋白质组数据分析的准确性；并发展新的数据分析方法研究UC状态下菌群代谢变化与菌群结构组成、蛋白质表达和翻译后修饰的相关性。本项目将为深入了解肠道菌群失调介导的UC病理机制和相应的菌群靶向治疗提供理论依据。

肠道菌群代谢紊乱与溃疡性结肠炎（UC）的发生发展密切相关，但由于肠道菌群的复杂性，目前依然缺乏对UC状态下肠道菌群代谢变化及其机制的系统性研究。本项目建立了一系列创新型的宏蛋白质组学方法，包括基于超低浓度胰酶剔除高丰度蛋白的深度宏蛋白组数据采集方法，快速鉴定蛋白酶调控图谱及单氨基酸多态性（SAPs）的宏蛋白组数据分析方法，对临床粪便样品的分析表明炎症性肠病（IBD）肠道菌与宿主的蛋白质-蛋白质关联网络发生显著变化，宿主与肠道菌关联互作的核心蛋白主要是蛋白酶CTRB2、CTRC、CELA3A，相对于克罗恩病(CD)，UC还具有特异性变化的核心蛋白ACTG2。本项目还首次系统地研究了状态下肠道菌微生态系统中蛋白酶切图谱以及SAPs变化，结果表明肠道菌群和宿主SAPs表达谱在IBD病人中显著变化且紧密关联，而代谢组学分析表明IBD状态下肠道内参与氧化应激等多个生物过程的代谢物显著变化，并进一步通过多组学数据关联分析解析了炎症性肠病中菌群结构组成、蛋白质表达和酶切调控、代谢变化的相关性。本项目将为深入了解肠道菌群失调介导的炎症性肠病病理机制和相应的菌群靶向治疗提供理论依据。