Preliminary Study On Intestinal Microflora And Metabolomics In Gestational Diabetes Mellitus

BackgroundGestational diabetes mellitus（GDM）refers to the abnormal glucose metabolism that is first discovered or occurs during pregnancy.It usually happens in the the second or third trimester of pregnancy and is one of the most common medical gestational complications.At present,the pathophysiological mechanism of GDM has not been fully elucidated.GDM is a multifactorial metabolic disorder in pregnancy and is well suited for studies by metabolomics.The intestinal microbiota is an important component of human body.Intestinal dysbiosis could lead to acute and chronic diseases.The intestinal microbiota also affects the metabolism and absorption of fat,impacting insulin resistance,which is closely related to the development of GDM.However,little is known about the relationship between changes in the intestinal microbial diversity and metabolism in patients with GDM.GDM is similar to that of type 2 diabetes.It is a multi-gene disease with many risk factors and has genetic heterogeneity.Genetic polymorphisms may cause differences in serum metabolites in GDM.Some studies indicated that host genetics controls the balance of intestinal micro-ecological system.Therefore,the analysis of GDM susceptibility genes,serum differential metabolites and intestinal microflora characteristics can provide a comprehensive understanding of its pathogenesis,which has important guiding value for early prediction,diagnosis and timely treatment of GDM.Section Ⅰ: Diversity of intestinal microflora in GDM Objective 1.To study the characteristics of intestinal microflora in patients with GDM,and to analyze the diversity and abundance of intestinal microflora.2.To explore the relationship between GDM and the changes of intestinal microflora.MethodsMid-term pregnant women of 24-28 weeks of gestation in the outpatient department of the Third Affiliated Hospital Zhengzhou University from February 2017 to December 2017 for glucose tolerance test（OGTT）were enrolled in the study.13 consecutive patients who met the diagnostic criteria for GDM were the experimental group（GH group）,11 consecutive normal pregnant women who matched with age and excluded pregnancy complications were used as a control group（NH group）,and collect fecal specimens.High-throughput sequencing of V4 region of bacterial 16 s r RNA gene was performed using the Illumina Mi Seq sequencing platform,and the results were analyzed by bioinformatics.Results1.Using 16 S r RNA high-throughput sequencing technology to analyze the difference of intestinal microflora between GDM patients and healthy pregnant women,the results showed that the abundance of intestinal microflora in GDM patients was lower than that in healthy pregnant women,and the distribution of microflora is different.In the GDM group,the intestinal microflora structure was significantly different（P<0.05）.2.At the level of genera,the abundance of Aggregatibacter,Campylobacter,Desulfovibrio,Gemmiger,Leptotrichia,Neisseria,Odoribacteria,Oxalobacter,Poromonas,WAL₁855D were lower than that of healthy control group（P < 0.05）.Among them,the abundance of Desulfovibrio,Jimmyella and Odoribacter was significantly reduced in GDM patients.3.LEf Se analysis indicated that methanobacteria,Archaea and Vibrio played an important role in the healthy group,while Haemophilus and Pasteurella played an important role in the gestational diabetes mellitus group.Brief summaryThe abundance of intestinal microbiota during mid-pregnancy was decreased in GDM patients compared with healthy pregnant women,and the distribution of microflora among individuals varied greatly.The decrease was particularly significant in the abundance of Desulfovibrio,Gemmiger,and Odoribacter.The microflora distribution varied greatly among individuals.Methanobacteria,Archaea,Desulfovibrio and Gemmiger played an important role in the second trimester of healthy pregnant women.Haemophilus and Pasteurella played an important role in the second trimester of GDM patients.Part Ⅱ Metabonomics study of pregnant women with GDM Objective1.Through HPLC-MS analysis of serum of GDM patients and healthy pregnant women,combined with metabolomics methods to initially screen differential metabolites.2.To analyze the pathway of differential metabolites,and to study its mechanism and biological significance.3.To explore the relationship among differential metabolites,intestinal microflora and GDM susceptibility genes.Methods1.Mid-term pregnant women of 24-28 weeks of gestation in the outpatient department of the Third Affiliated Hospital Zhengzhou University from January 2016 to June 2016 for glucose tolerance test（OGTT）were studied.Non-targeted metabolomics study was performed on the serum of 30 GDM volunteers and 30 healthy pregnant volunteers by HPLC-MS.Search the differential ions between the two groups2.Identification of differential metabolites by HMDB database;3.The metabolic pathways of different metabolites were analyzed by KEGG database.4.Through KEGG pathway analysis,susceptible genes closely related to the changes of intestinal microflora and metabolites in GDM were screened.Results1.The serum metabolism in GDM patients was significantly different from normal pregnant women.2.With Fold change ≤0.8333 or ≥1.2,and P < 0.05 as screening criteria,36 differential metabolites and multiple metabolic pathways were identified in serum.Among them,the metabolites such as TXB2,11-dehydro-TXB2,PGs,LTs,Linoleic acid,Cholesterol,LPA,lysophosphatidylcholine,and docosapentaenoic acid were up-regulated or down-regulated in GDM.3.These differential metabolites are mainly concentrated in multiple metabolic pathways such as fatty acid metabolism,steroid hormone biosynthesis,amino acid metabolism,and bile secretion.4.Three susceptible genes,TCF7L2,TNF-α and PPARγ were screened out.Brief summary1.36 differential metabolites may be potential biomarkers for GDM.2.These metabolites were mainly involved in fatty acid metabolism,steroid biosynthesis,arachidonic acid metabolism,butyric acid metabolism,amino acid metabolism and bile secretion pathways.3.GDM-related genes may affect the changes of serum metabolites and intestinal microbiota characteristics in pregnant women with GDM by participating in glycolipid metabolism and inducing inflammation respectively,which may provide a theoretical basis for further research on the pathogenesis,early prediction and individualized treatment of GDM.