A Study On Gestational Microbiota And SIgA-targeted Lactobacillus Intervention For Gestational Diabetes Mellitus In Vitro

Gestational complications such as gestational diabetes mellitus(GDM)and gestational hypertension(GH)affect the health of the fetus and pregnant women,and increase the probability of metabolic diseases in the offspring.These complications are the result of abnormal immune and metabolic changes from early pregnancy to late pregnancy,and are related to the imbalance of gut microbiota.Therefore,probiotic intervention is a potential nutritional precaution to prevent pregnancy complications.The purpose of this study was to analyze the differences of gut microbiota between healthy pregnant women and GDM pregnant women,and to provide information for the isolation of human probiotics for the prevention of GDM.The main contents are as follows:First,fecal samples of healthy pregnant women in early pregnancy(n=50)and late pregnancy(n=50)were collected to analyze the composition characteristics of total fecal microbiota and fecal sIgA-coated microbiota.The results showed that there was a significant difference in the total gut microbiota β-diversity of healthy pregnant women between early and late pregnancy.The result of α-diversity including Shannon index and Simpson index showed that the total gut microbiota diversity of healthy pregnant women in the third trimester was significantly higher than that of healthy pregnant women in the first trimester(P<0.01).Faecalibacterium,Roseburia and Prevotella were the dominant genus in early healthy pregnant women,Faecalibacterium,Blautia and Bifidobacterium were the dominant genus in late healthy pregnant women.Compared with healthy pregnant women in early pregnancy,fecal sIgA-coated Bacteroidetes and Firmicutes in late pregnant women were significantly reduced(P<0.01),Actinobacteria and Proteobacteria were significantly increased(P<0.01).Enterococcus is the dominant genus in fecal sIgA-coated microbiota of all samples.Blood biochemical analysis showed that from the first trimester to the third trimester,the levels of blood glucose,blood lipid and inflammatory factors showed an increasing trend.Second,compare and analyze the composition of gut microbiota among healthy pregnant women,GDM and GH pregnant women in the third trimester.The results showed that the total fecal microbiota composition of healthy and the two pregnancy complications pregnant women in late pregnancy was similar.However,PCA analysis of sIgA-coated microbiota could divide all samples into three groups.The dominant pregnant individuals in each group were healthy(AHd),GDM(GDMd)and GH(GHd)pregnant women,respectively.Enterococcus,Staphylococcus and Escherichia were the dominant fecal s IgA-coated microbiota of three groups,respectively.The result of α-diversity Shannon index showed that GDMd and GHd had higher sIgA binding diversity(P<0.01).Compared with AHd group,pregnant women with GDMd and GHd groups had significantly higher levels of serum intestinal mucosal barrier injury indicator Zonulin,inflammation markers including fecal calprotectin and glycosylated cellular adhesion molecules.SIgA-coated L.reuteri was negatively correlated with inflammatory factor fecal lipopolysaccharide(FLPS,P<0.05).Hyperglycemia can interfere with the integrity of the intestinal epithelium,resulting in intestinal mucosal barrier damage,abnormal intestinal permeability to lipopolysaccharide,andinflammatory response.So L.reuteri may inhibit inflammation to prevent pregnancy complications.Third,five strains L.reuteri,four strains L.fermentum,six strains L.salivarius were isolated from healthy pregnant women feces,their probiotic potential was preliminarily studied and compared with typical probiotics,including L.rhamnosus HN001 and L.fermentum CECT5716.The results showed that L.reuteri had the best acid tolerance,bile salt tolerance,hydrophobicity and adhesion abilities,similar to L.rhamnosus HN001 typical probiotics.Then,simulated colonic single batch fermentation(24 h)was performed on the gut microbiota of pregnant women with GDM(n=5),and L.reuteri LR-2 and L.rhamnosus HN001 were added for intervention.The results showed that L.reuteri LR-2 could significantly increase the production of acetic acid,reduce the release of lipopolysaccharide(LPS),and reduce the abundance of Proteobacteria.In conclusion,the imbalance of sIgA-coated microbiota in the third trimester is related to the occurrence of pregnancy complications.One of the potential bacterial species in the sIgA-coated microbiota that can inhibit inflammation is L.reuteri.The strain L.reuteri LR-2isolated in this study could inhibit inflammation caused by intestinal microbiota imbalance in GDM pregnant women in vitro,and its preventive effect of GDM needs further study.