幼龄山羊回肠细菌定植调控与外周血免疫系统的关联机制及计算模型解析

Plenty of commensal bacteria inhabits in the mucosa epithelium and chime of the ileum of goat. These commensal bacteria, colonizing in the gastrointestinal tract (GIT), can interact with the host’s immune system (especially the mucosal immune system, MIS) via signal transmissions or regulation factors (such as GPR43, GPR109A, sIgA, CARD9, NOD1, and sex hormone). Compared to MIS, the peripheral blood immune system (PBIS) is rich in immune factors, like interleukin, leukocytes, and complement proteins. It is of great difficulty to explore the interactions between the PBIS and intestinal microflora only by using traditional experimental technics, for there’s no direct contact between them. However, exploring the interaction between the ileal microbiota and PBIS may help us to have a better understand of the interaction between host and microbiota. In this project, we intend to use young goats (70 days of age) as experimental animals, with to Astragalus extract in the form of nanoparticles and micellar granules added to the diet as experimental treatments, to study the interaction between microbiota and PBIS in the ileum. Experimental data of the microbiota (bacterial metabolites, genomics and transcriptomics) and PBIS (interleukins, complement proteins, pattern recognition receptors, etc.) will be obtained by high-throughput sequencing, macrography, metabolomics, q-PCR and other techniques, then, a mathematical model of the association mechanism between ileal microbiota and PBIS will be constructed by using bioinformatics, machine learning algorithms, computational modelling and complex networks. It aims to use the established mathematical prediction models to digitize the complex association networks of ileal microbiota colonization and the peripheral blood immune system, and provide a scientific basis for the optimization of dietary formula and feeding management in actual production.

山羊回肠粘膜上皮及食糜中栖息着大量固有菌群。定植的共生菌可通过诸如GPR43、GPR109A、sIgA、CARD9、NOD1及性激素等信号转导或调控因子与机体免疫系统（如粘膜免疫系统）产生互作。外周血液中含有丰富的免疫因子，但由于外周血与肠道微生物之间没有直接接触，故鲜有关于二者互作关系的评价，而研究这二者的关联机制将有助于理解机体与肠道细菌之间的互作关系。本项目拟以幼龄山羊为试验动物，经日粮中添加纳米和胶束颗粒的黄芪提取物作为试验处理，利用高通量测序、宏转录组学、代谢组学、q-PCR等研究手段，获取回肠菌群和外周血免疫系统的基础数据，进而利用生物信息学、计算模型算法和复杂网络等分析方法，构建山羊回肠细菌定植调控与外周血免疫系统间的关联机制的数学预测模型。旨在利用建立的数学预测模型，将回肠细菌定植与外周血免疫系统的复杂的关联网络数字化，为实际生产中日粮配方优化和饲养管理提供科学依据。

幼龄山羊肠道微生物与宿主机体免疫系统存在复杂交互作用。外周血与肠道菌群无直接接触，故鲜有关于二者互作关系的报道，而研究这二者的关联机制将有助于理解机体与肠道细菌的对话机制。本项目以幼龄山羊为试验动物，饲喂黄芪根超微粉（AP）并建立IBD模型（DSS），获取回肠、盲肠菌群微生物多样性和外周血免疫系统等基础数据，并利用生物信息学、机器学习算法等分析方法，构建山羊回肠细菌定植调控与外周血免疫系统间的关联机制的数学预测模型。结果显示：AP显著提高幼龄山羊补体蛋白C3、C4、IgA、IgM和IgG含量，而DSS增加C1q含量，且AP和DSS均可提高C4bp含量，但对Factor H无影响；AP提高十二指肠脂肪酶活性、空肠淀粉酶和糜蛋白酶活性及回肠脂肪酶活性；AP提高断奶山羊十二指肠和空肠淀粉酶、脂肪酶和糜蛋白酶基因，及回肠淀粉酶、脂肪酶、胰蛋白酶和糜蛋白基因的基因表达；DSS诱导炎性肠病减少羔羊盲肠中乙酸和部分有益菌数量，但提高丁酸产量以及丁酸合成细菌的丰度进而减轻肠道炎症；通过相关性分析，回肠黏膜免疫屏障指标间呈正相关性，如TJP1和TJP3（r=0.69, P<0.05），FOXP3与TJP2（r=0.68, P<0.05）和IL7呈（r=0.67, P<0.05），TJP2和IL7（r=0.98, P<0.05），MUC2和TNFａ呈正相关性（r= 0.61, P<0.05）；而F11与TJP2（r=-0.44, P<0.05）和IL7 （r=-0.45, P<0.05）呈负相关；山羊回肠优势菌包括Firmicutes, Proteobacteria和Verrucomicrobiota（门水平），但个体差异明显；其丰度排序为Romboutsia, Mycoplasma和Clostridium（属水平）。综上，肠道菌群与宿主免疫系统存在着广泛的交互作用。