肠道菌群基因组对妊娠期糖尿病发病的影响及其机制研究

Gestational diabetes mellitus (GDM) is a common obstetric complication in pregnancy, which appears the phenomenon of mild hyperglycemia after 24 weeks in pregnancy. GDM will produce serious adverse effects on mothers and infants, such as premature, eclampsia, macrosomia, and will increase the long-term effect on the occurrence of metabolic syndrome for mothers and infants. Although many factors are related to GDM, the pathogenesis of GDM remains unknown. Previous studies showed that the insulin resistance caused by chronic inflammatory reaction is an important mechanism for the pathogenesis of GDM. Recent studies found that gut microbiotic disturbance could promote chronic inflammation in diabetes, obesity and other diseases, which is related to the occurrence of insulin resistance. As we all known, the pathogenesis of GDM is similar to type 2 diabetes. So, we proposed that the gut microbiota is related to GDM and may be involved in the pathogenesis of this disease. We found that there are few researches on the gut microbiota with the pathogenesis of GDM. In this study, we will use a prospective clinical cohort to explore the relationship between gut microbiota and GDM by metagenomic sequencing technology. Based on the research, we will found specific microbiota for GDM, thus providing possible predictive and intervention methods. We will establish an intestinal microbiota transplantation animal model, and we hope to verify the hypothesis that the change of intestinal flora may alter intestinal mucosa permeability, which may stimulate TLR4 pathway to participate in the occurrence of gestational diabetes mellitus. Moreover, we will design an intestinal microecological preparation intervention experiment, in order to provide an evidence for the development of intestinal flora biological agents in patients.

妊娠期糖尿病（GDM）是产科最常见的并发症，GDM在妊娠期由于胰岛素抵抗出现血糖升高，会增加母儿近远期并发症的产生，如巨大儿、成年期肥胖、2型糖尿病等。GDM的发病机制是医学领域研究热点之一，慢性非特异性炎症反应引起的胰岛素抵抗是GDM发病的重要机制。最新研究发现，肠道菌群失调通过促进慢性非特异性炎症反应参与了糖尿病、肥胖等的发生，但目前尚无孕期肠道菌群与GDM发病及其调控机制的研究。本研究拟通过宏基因组测序技术明确肠道菌群与GDM发病的关系，筛选GDM致病菌群，为临床提供预测和干预GDM发病的评价指标；构建GDM孕妇肠道菌群植入动物模型，验证肠道菌群失调可能通过改变肠道粘膜通透性，激活Toll样受体4慢性非特异性炎症通路，参与了胰岛素抵抗及GDM的发生，为GDM的病因学研究提供新的思路；通过肠道微生态制剂干预实验，为临床开发肠道益生菌预防及治疗GDM提供实验依据。

本研究从2017年1月开始，基本按照计划进行。利用课题组已建立临床队列，分别比较妊娠期糖尿病(Gestational Diabetes Mellitus, GDM)孕妇和正常孕妇发病初期、治疗前后肠道菌群构成差异，为临床提供干预指标。建立菌群移植孕鼠模型，验证肠道菌群通过炎性通路在GDM发病中的作用；进一步比较正常孕妇不同妊娠时期及产后菌群构成差异，探索妊娠对菌群构成的影响及变化规律；通过子代菌群影响因素研究，探讨生命早期菌群建立特征和关键因素。. 研究GDM孕妇肠道菌群特征性变化，发现其α多样性降低， LEfSe分析属水平上Akkermansia等在正常孕妇高表达，Blautia等在GDM孕妇中表达较高；将上述菌群构成和血糖、炎症因子进行相关性分析，Akkermansia等优势菌群与血糖负相关，厚壁菌门丰度与炎症因子水平呈正相关，反之亦然。将GDM孕妇和正常孕妇粪便分别移植于无菌小鼠，结果发现接受前者粪便的无菌小鼠，血糖水平高于对照组。经过规范化治疗后，GDM孕妇血糖和菌群构成均趋于正常。. 正常孕妇妊娠期及产后肠道菌群变化规律研究中，α多样性提示孕晚期较孕早期菌群丰度和均一度均有上升，而Unifrac distance结果显示，不同孕妇个体间的肠道菌群随妊娠过程趋于相似；随访至产后6个月，菌群构成与妊娠期差异显著。. 对生后6周婴儿粪便标本进行测序，按照分娩方式进行分组，β多样性提示剖宫产组菌群构成改变明显，且Bifidobacterium在顺产组丰度较高，Lactobacillus等在剖宫产组丰度较高；按照喂养方式进行分组，α多样性及β多样性差异较小，LEfSe分析发现，混合喂养婴儿纲水平Negativicutes、目水平Selenomonadales、科水平Veillonellaceae和Enterococcaceae，以及属水平Veillonella和Enterococcus丰度较高。将两类因素进行综合分析，发现纯母乳喂养可以改善由于剖宫产导致的菌群构成紊乱。出生后抗生素暴露对婴儿生后6周时肠道菌群构成影响小。. 目前本课题培养博士研究生5名，发表8篇论文（SCI 4篇，核心期刊4篇）。通过已建立临床队列和菌群移植动物模型，探讨肠道菌群在妊娠期糖尿病发病中的重要作用、生命早期建立的影响因素，为深入病因学研究奠定基础、为临床干预提供实验依据。