德氏乳杆菌对哺乳仔猪肠道树突状细胞（DC）发育影响及其信号通路研究

The major function of the Lactobacillus on the animals is to enhance the immune response in the gastrointestinal tract of the animals, thus the investigation of the underlying mechanisms on the effects of Lactobacillus on the muscoal immune function may shed light on the development of Lactobacillus-based probiotic and its good application. The study aimed at evaluating the effect of oral administration of Lactobacillus delbrueckii on the distribution, production and maturation of the dendritic cells(DCs), the distribution of the Toll-like receptors (TLRs) and its changes of the positive expression area in the intestinal of the suckling piglets using immunohistochemical techniques and real time PCR techniques. The levels of mRNA expression of TLR2,TLR4,MyD88 and some cytokines are also investigated using the same techniques mentioned above.Therefore reveals the regulatory role of the Lact. delbrueckii on the suckling piglets intestinal DCs development. By analyzing the maturation markers of the cell and the cytokine profile in the culture medium from in vitro culture of the pig bone marrow-derived DCs, the effects of Lact. delbrueckii and its cellular components to regulate the DC maturation differences and the material basis through which it play its immunomodulatory roles are clarified. By evaluating the mRNA expression of DC surface receptors TLRs and their major downstream signal transtraction pathway components, the signal transtraction pathways by which Lact. delbrueckii regulate DC maturation are revealed. Therefore, the main objective of this study is to reveal the immnuomodulatory mechanisms of the Lactobacillus delbrueckii through cell and molecular level and form the theoretical basis for the development of Lact. delbrueckii-based probiotic and its application in the livestock production.

乳酸菌具有增强动物黏膜免疫反应的重要作用，探明乳酸菌促进黏膜免疫反应的机理是开发理想乳酸菌制剂及合理应用的关键。本研究应用免疫组织化学技术及实时荧光定量PCR技术考察哺乳仔猪灌服德氏乳杆菌菌液后仔猪肠道树突状细胞（DC）的分布、数量、成熟度及病原识别受体TLRs的分布及其阳性表达面积的变化、肠道粘膜组织中TLR2、TLR4、MyD88及部分细胞因子 mRNA的表达，揭示德氏乳杆菌对哺乳仔猪肠道DC免疫功能的调控作用。通过体外培养猪骨髓来源DC，分析DC的成熟标志分子及细胞培养液中细胞因子含量，阐明德氏乳杆菌及细胞组分调节DC成熟的差异性和德氏乳杆菌发挥免疫调节作用的物质基础。对DC表面受体TLRs及其下游信号转导通路主要元件mRNA进行表达，揭示德氏乳杆菌调节DC成熟的信号转导途径。本研究旨在细胞水平和分子水平上探讨德氏乳杆菌免疫调节机理，为乳酸菌制剂的开发和在畜牧生产中应用提供理论依据。

本研究应用免疫组织化学技术及实时荧光定量PCR技术考察哺乳仔猪灌服德氏乳杆菌菌液后仔猪肠道树突状细胞及肠道粘膜组织中TLR2、TLR4、MyD88及部分细胞因子 mRNA表达的影响，本研究旨在揭示德氏乳杆菌对哺乳仔猪肠道DC免疫功能的调控作用，在细胞水平和分子水平上探讨德氏乳杆菌免疫调节机理，为乳酸菌制剂的开发和在畜牧生产中应用提供理论依据。   .研究发现，德氏乳杆菌可以增加小肠空肠、回肠黏膜固有层DC的数目；能够促进肠黏膜TLR2、TLR4的表达增加，促进相关细胞因子mRNA和蛋白水平的表达尤其是IL-2 mRNA的表达，在正常生理水平下，外服德氏乳杆菌能下调哺乳仔猪肠黏膜Th1型免疫反应，可能在T细胞向Th2型细胞分化方面起了促进作用。乳酸杆菌对细胞因子产生水平的调节可能是维护黏膜免疫功能的重要机制。.哺乳期仔猪灌服德氏乳酸杆菌能改善仔猪免疫相关细胞因子的分泌情况，增加肠道上皮内淋巴细胞数量和杯状细胞数量，能够在一定程度上促进肠道紧密连接蛋白Occludin和ZO-1的表达，进而发挥抗病防腹泻作用，提高仔猪的生产性能。.该项目取得了较好的研究成绩。该项目的研究，为后期研究打下了很好的基础，获得了2014年国家自然科学基金项目资助（31372322）。已发表论文4篇；获得授权国家发明专利1项，获得大北农科技三等奖1项；培养博士后1名，博士生1名，硕士生2名。