肠道菌群变化与原发性胆汁性肝硬变发生发展的关系与机制研究

The prevalence of PBC is rising worldwide. Many factors such as susceptibility genes, the bile circulation, infections, xenobiotics and the autoimmunity are thought to contribute to the onset of PBC, but the etiology and pathogenesis this disease is still unclear. As a result, PBC cannot be prevented and cured up to now, leading to heavy family and social burdens, and even to a life-threatening event. . Intestinal flora is the largest human microbial pool. It can transform, utilize and produce a lot of xenobiotics, participate in the enterohepatic circulation of bile acids, regulate immunity, prevent the invasion of exogenous bacteria, cause endogenous infection under the condition of microbiota imbalance. Two papers that separately published on Lancet and Nat Immunol are of the view that the intestinal flora is a mystery of etiology and pathogenesis of PBC, but so far there is no study. We found some alterations of species and metabolisms of the human intestinal flora early in PBC. In this project, we aim to fully understand the alterations of structures and functions of human intestinal flora in PBC, to check whether the altered intestinal flora can induce PBC in healthy mice, and to disclose the functions and mechanisms of altered intestinal flora to the PBC mouse model. The expected results of this project have important significance to etiology, pathogenesis, diagnosis and treatment of PBC.. Since this project was supported by the State Key Laboratory, guided by a world famous microbial ecologist, conducted by members who have published articles in Nature and Hepatology, constructed on a solid foundation, we think it is feasible.

原发性胆汁性肝硬化（PBC）患病率不断上升，与易感基因、胆汁循环、感染、异生物质和自身免疫有关，但病因和发病机理不明，无法预防和根治，造成沉重家庭社会负担，甚至威胁患者生命。肠道菌群是人体最大菌库，能转化、利用、产生大量外源物，参与胆汁酸肠肝循环，调节免疫，防止外源菌入侵，失衡时导致内源性感染。Lancet和Nat Immunol论文均认为肠道菌群是PBC病因和发病机理的神秘面纱，但迄今尚无研究。我们前期发现PBC患者肠道菌群种类和代谢改变。本项目将利用宏基因组、代谢组、无菌动物和分子免疫等，全面揭示PBC患者肠道菌群的结构功能变化规律、诱导健康小鼠发生PBC能力、及其对SPF小鼠PBC模型的作用与机制。预期成果对PBC病因、发病机制、诊断和防治具有重要意义。项目以国家重点实验室支撑，聘请微生态学家指导，成员曾在Nature、hepatology发表论文，基础扎实，技术完备，有较高可行性。

原发性胆汁性肝硬化（PBC）是一种慢性肝内胆汁淤积性疾病。目前， PBC 患病率总体呈上升趋势，其根本原因是病因和发病机理不明导致的无法预防和根治，造成了沉重的家庭和社会负担，甚至威胁患者生命。本项目利用宏基因组、代谢组、无菌动物和分子免疫等，全面揭示PBC患者肠道菌群的结构功能变化规律、诱导健康小鼠发生PBC能力、及其对SPF小鼠PBC模型的作用与机制。国际上率先利用16S rDNA技术揭示了PBC患者的肠道菌群变化规律，PBC肠道菌群表现出环境敏感菌减少甚至灭绝，某些有益菌及拟杆菌或变形菌中的少量条件致病菌在PBC中减少，一些健康人少见的条件致病菌在PBC肠道大幅增加。免疫组研究发现，PBC患者机体存在严重的炎症反应，PBC患者的肝功能与免疫变得密切相关，肝损伤因子例如AST和ALP和GGT与IP-10, MIG等关联，通过这些与IL-16等关联，形成复杂网络。HC和PBC的血清、粪便和尿液代谢组轮廓明显区分，PBC血清磷脂酰胆碱等丰度改变，PBC尿液中色氨酸、胆汁酸等丰度改变，PBC粪便中色氨酸、胆汁酸等相关产物丰度改变。PBC患者代谢产物变得与免疫和相互关联，PBC中改变的肠道细菌约50%与胆汁酸和磷脂相关，相对丰度在PBC中改变的一些微生物和色氨酸代谢产物相关，部分PBC改变的肠道菌群与谷氨酰胺代谢密切相关。发现PBC患者口腔唾液微生态中Bacteroidetes显著升高，炎症因子和有害代谢物升高，刷牙后炎症减少、代谢轮廓明显改变与健康对照类似。对PBC患者的肠道菌群进行了宏基因组、真菌组进行了检测，并与其他自免病的进行对照，发现肠道菌群中的胆汁酸和炎症相关功能基因发生了明显的改变。利用PBC患者和健康对照的粪便对SPF、抗生素脱污小鼠（无菌小鼠）及其PBC模型进行灌胃，发现PBC患者肠道菌群能够诱导PBC样病变，其机制与破骨细胞分化相关途径相关。项目在Environmental microbiology, Journal of Proteomics等发表标注基金号的论文14篇。迄今为止，项目研究结果已经初步确认肠道菌群及其产物在PBC的发生中具有重要的作用，后续将对发现的关键机制进行深入研究。