Study On The Relationship Between Gut Microbiota And Allergic Diseases In Infants

Objective:Analyzed the gut microbiota of infants with allergic diseases and healthy infants,explored the relationship between gut microbiota and allergic diseases in infants,identified specific microbiota related to allergic diseases,and provided scientific basis for the prevention and treatment of allergic diseases in infants.To analyze the composition and the dynamic changes of the relative abundance of gut microbiota in infants at the early stage of life and at different time points(0 months,6months and 12 months),to provide a scientific basis for the possible prediction function of gut microbiota in early life for infant allergic diseases.Method: Based on the established cohort of infants and children,they were followed up to 1 year old.Combined with the diagnosis of clinical allergist,57 infants meeting the criteria were selected for case-control study,including 37 infants with allergic diseases within 12 months and 20 healthy controls,which were grouped into the allergy group(A)and the non-allergic group(NA).The stool samples of infants in the two groups at 0 months(newborn),6 months and 12 months were named respectively as A0 M group and NA0 M group,A6 M group and NA6 M group,A12 M group and NA12 M group according to the collection time(month,M)of stool samples.The basic information of the subjects was collected by questionnaire and telephone follow-up.After the bacteria were amplified by two-step PCR,the V3-V4 region of 16 S rRNA was sequenced using Illumina Hiseq2500 high-throughput sequencing platform.Results: 1.The species annotation results of infant gut abundance showed that at the phylum level,Proteobacteria,Firmicutes,Actinobacteria and Bacteroidetes were the dominant bacteria in the gut microbiota of infants aged 0 months,6 months and 12 months.However,the order from high to low and the relative abundance of dominant phyla were different at different time points,the relative abundance of Proteobacteria was the highest at 0 month(44.97%),that of Actinobacteria was the highest at 6months(34.05%),and that of Firmicutes was the highest at 12 months(33.92%).At the genus level,Escherichia-Shigella had the highest relative abundance at 0 month,while Bifidobacterium had the highest relative abundance at 6 and 12 months.2.Meta Stats analysis showed that the relative abundance of Bacteroidaceae,Bacteroides and Erwinia in A0 M group at 0 month was significantly higher than that in NA0 M group(P<0.05);At 12 months of age,the relative abundance of Pasteurellales,Streptococcaceae,Pasteurellaceae,Streptococcus and Haemophilus in A12 M group was significantly higher than that in NA12 M group(P<0.05).3.Based on the independent sample T test,there were no statistically significant differences in gestational age,height,weight,feeding style,time of supplementary food addition,residential history,smoking exposure and animal contact history between allergic and non-allergic groups(P>0.05);There were statistically significant differences in gender and family history of allergic disease between allergic and non-allergic groups(P<0.05).4.There was no significant difference in the Alpha diversity index between the A0 M and NA0 M groups(P>0.05);The Observed-species index and Chao1 index in A12 M group were significantly higher than those in NA12 M group(P<0.05).In the hierarchical analysis of gender and family genetic history,the Chao1 index of gut microbiota in the A12 M group was significantly higher than that in the NA12 M group(P<0.01),and no statistical difference was observed between the two groups in gender of the hierarchical analysis.5.In the Beta diversity analysis,PCo A/ PLS-DA analysis showed that there was no statistically significant difference in community structure between the A0 M and NA0 M groups;The differences in community structure between A12 M and NA12 M groups were statistically significant,and Anosim similarity analysis showed significant differences between the two groups(P<0.05).6.Spearman correlation analysis was conducted between gut microbiota of infants and their general situation,family situation and other environmental factors.Bacteroides was positively correlated with animal exposure(r=0.31,P<0.05),and negatively correlated with its hospitalization history(r=-0.35,P<0.001)and solid food intake time(r=-0.30,P<0.05);Pasteurellaceae was positively correlated with feeding style(r=0.30,P<0.05)and duration of breastfeeding at 6 months(r =0.28,P<0.05);Streptococcus was negatively correlated with hand-foot-mouth disease vaccine(r=-0.31,P<0.05),Haemophilus was positively correlated with father’s history of allergy(r=0.27,P<0.05).7.Kruskal-wallis H test was used to compare the changes of gut microbiota at three different time points in the first year after birth between the allergic group and the non-allergic group.At the phylum level,the relative abundance of Proteobacteria,Firmicutes and Actinobacteria in the intestinal tract of the two groups showed similar trends over time at 0 month,6 months and 12 months.The relative abundance of Bacteroidetes in the two groups showed the same trend from 0 to 6 months,but the opposite trend from 6 to 12 months.At the genus level,the relative abundance of Streptococcus showed a completely opposite trend between the two groups,and the relative abundance of Streptococcus at each time point in the allergic group was higher than that in the non-allergic group.Conclusion: 1.Pasteurellales,Streptococcaceae,Pasteurellaceae,Streptococcus and Haemophilus were significantly enriched in the allergy group,suggesting that the development and progression of allergic diseases in infants is closely related to specific microbiota,and the relative abundance of streptococcus in the two groups of infants has a completely opposite trend with the increase of their age,suggesting that the increase of relative abundance of streptococcus may be a potential key indicator of increased risk of allergy.2.The significant difference of Bacteroides and Erwinia in the early stage of life(0month)between the two groups suggests that it can predict the occurrence of allergic diseases later in infant.These evidences may provide new ideas for the prevention and treatment of allergy in infants through early probiotics intervention.3.Animal history of exposure,hospitalization time,solid food intake,feeding methods,within 6 months breastfeeding duration,hand-foot and mouth disease vaccine,genetic father allergy history associated with infant gut microbiota,suggesting that environmental factors may affect intestinal symbiotic bacteria in infants,but their role in the occurrence and development of allergic diseases in infants needs further exploration.4.The relative abundances of Proteobacteria,Firmicutes,Actinobacteria and Bacteroidetes in the intestinal tract of infants aged 0-12 months changed with the increase of age.The results showed that the gut microbiota of infants in early life was in a dynamic construction process.