Characteristics Of Intestinal Flora In Atopic Dermatitis Patients

Objective:The study is designed to investigate the composition and distribution of gut microbiota in patients suffering from atopic dermatitis,then determine the difference of gut microbiota among patients before and after the treatment as well as normal controls in order to filter microbial biomarkers associated with atopic dermatitis,so as to provide some new ideas for the treatment of atopic dermatitis by regulating the gut microbiome.Methods:Patients admitted to Jinling hospital from April 2018 to August 2018 are included in this study according to inclusion and exclusion criteria.Twelve patients are enrolled as case group.Age matched healthy individuals are the control,and their stool samples are collected as N group.Patients are given treatment for 2 months.Before and after the treatment,they are taken pictures to evaluate the severity of the disease according to Scoring Atopic Dermatitis index(SCORAD)and their stool samples are collected.The score and stool samples of patients are divided into groups and named as B group and A group,respectively.16S r DNA sequencing is used to investigate the composition and distribution of gut microbiota in patients and normal people.Species components analysis,alpha diversity,beta diversity,and linear discriminant analysis are used to investigate the difference among three groups.Microbial biomarkers associated with atopic dermatitis are filtered by LEf Se analysis and spearman correlate analysis.Results:1.At phylum level,three groups have similar predominant flora known as Firmicutes,Bacteroidetes,Proteobacteria and Actinobacteria.At genus level,three groups have similar predominant flora known as Blautia,Bacteroides,Faecalibacterium and Bifidobacterium.2.There is no significant difference of alpha diversity between case group and normal controls,or between B group and A group.Rarefaction curve indicates that the sequencing depth is not deep enough.Rank-abundance curve shows no difference is observed in evenness and B group contains the most species among three groups.3.Principal coordinates analysis shows the composition of the gut flora of N group and A group tends to be more similar,while the gut flora of B group tends to be more different.4.LEf Se analysis indicates Bacilli and Lactobacillales are the biomarkers of A group while Coprobacillus is the biomarker of B group.5.Spearman correlate analysis shows the severity of atopic dermatitis is positively correlated with the abundance of Ruminococcus and Faecalibacterium.Conclusion:1.The composition and distribution of gut microbiome is different between patients with atopic dermatitis and healthy people.Bacilli,Lactobacillales and Coprobacillus may play a role in the pathogenesis of atopic dermatitis.2.At phylum level three groups have similar predominant flora.At genus level,the comparison of the relative abundance turns out no significant difference among three groups.Alpha diversity among three groups shows no significant difference as well.3.The composition of gut flora of case group has changed and is more similar to normal group after the treatment.4.The biomarkers of A group are Bacilli and Lactobacillales,while the biomarker of B group is Coprobacillus.Bacilli,Lactobacillales and Coprobacillus may play a role in the pathogenesis of atopic dermatitis.5.The severity of atopic dermatitis is positively correlated with the abundance of Ruminococcus and Faecalibacterium,but fine-level characterization of bacterial subspecies is needed for different subspecies may have distinct activities.