GLP-1工程益生菌的构建及其对糖尿病治疗的微生物生态学和分子生物学机制研究

胰岛素分泌缺陷或作用受损而导致的糖尿病（DM）对人体健康和社会经济造成重大危害。申请者团队前期利用质粒过表达系统构建了一株可持续表达胰高血糖素样肽-1（GLP-1）的乳酸乳球菌，口服该工程菌可显著降低DM小鼠血糖，改善肥胖小鼠体重和胰岛素抵抗（见前期工作基础）。然而质粒过表达系统不稳定、易耐药等缺陷限制了其成药性，因此申请人将GLP-1基因整合入益生菌Nissle 1917染色体，在回避上述缺陷的同时确保了该整合型工程菌GLP-1产量，其可显著缓解DM小鼠糖尿病症状（见预实验结果）。本项目拟采用I型DM小鼠和II型DM小鼠，从小鼠糖脂代谢、胰岛β细胞功能、胰腺组织炎症反应、结肠炎症及肠壁通透性、肠道菌群及代谢产物改变等方面系统研究整合型工程菌对DM的疗效及作用机制，为DM患者研制出安全性好、针对性强、毒副作用小、价格低廉的口服型降糖药物提供理论支持。

Diabetes caused by insulin secretion defects make major harm to human health and socio-economics. In previous studies, our group constructed an engineered Lactococcus lactis that could continuously express GLP-1 (plasmid overexpression system), and oral administration of this engineered bacteria could significantly reduce blood glucose in DM mice, improve weight and insulin resistance in obese mice (see previous work). To avoid the drug resistance and unstable plasmid caused by overexpression system, our group integrated the GLP-1 gene into the probiotic Nissle 1917 chromosome, and the engineered E. coli 1917-attb-pelB-GLP-1 could produce sufficient amount of GLP-1, significantly relieved the symptoms of diabetes in DM mice (see previous work). In this project, a T1DM mice model and a T2DM mice model will be developed, and the treatment effect of E. coli 1917-attb-pelb-GLP-1 on DM will be systematically studied, via evaluating its influence on glucose and lipid metabolism, islet β cell function, pancreatic tissue inflammatory response, inflammation and permeability in the colon, intestinal microbiota and metabolites change. This provides theoretical support for the development of oral drugs for DM patients, with good safety, strong pertinence, non-toxic side effects and low price.