Gut Microbiota Structure And Function In Children With Autism Spectrum Disorder

Objective Autism spectrum disorder(ASD)is a neurodevelopmental disorder with great harm and onset of disease in infancy,which is lack of effective drug therapy,and the incidence is increasing year by year.At present,the specific etiology of the disease is still unclear,but generally speaking,it is the result of both genetic and environmental factors.Studies have shown that there is a correlation between gut microbiota as one of the important environmental factors and ASD.Therefore,the study of intestinal microbiota in children with ASD is expected to further explain the etiology and mechanism of ASD.Although previous studies have found the characteristics of gut microbiota in children with ASD are different from those in typically developing(TD)children,the number of studies is small and most of them have different results.In order to further clarify the similarities and differences in the characteristics of gut microbiota between ASD and TD children,and to provide a basis for exploring the specific correlation between ASD and gut microbiota,the differences in structure and function of intestinal microbiota between ASD and TD children were analyzed in this study.Methods Thirty children diagnosed in the pediatric neurorehabilitation clinic of our hospital were selected as ASD group,and twenty TD children were recruited into TD group for control.Feces were collected from 2 groups of children and fecal samples DNA were extracted.After passing the quality test,the V4 region of bacterial 16 s r DNA was amplified by PCR with primers 515F(5’-GTGCCAGCMGCCGCGGTAA-3’)and806R(5’-GGACTACHVGGGTWTCTAAT-3’).The purified amplified products were sequenced by high-throughput sequencing technology after passing the quality test.The amplicon sequence variants(ASVs)were obtained by splicing,quality control,filtration,removal of chimera and denoise of the original data got from the sequencing.The representative sequence of ASVs were annotated based on Silva138 database.Based on the annotation information,the microbiota structure was analyzed,the function was predicted,and the differences between groups were compared.Results The relative abundance of the top four phylum in the two groups of samples are the same,followed by Firmicutes,Bacteroidota,Actinobacteriota and Proteobacteria.The genus with the highest relative abundance in both groups is Bacteroides,followed by Faecalibacterium.There was no significant difference in alpha diversity index(Chao1,Shannon and Simpson)of gut microbiota in children between ASD and TD groups(P > 0.05).At the phylum and class levels,there was no significant difference in the structure of gut microbiota between the two groups(P > 0.05).At the genus level,the abundance of Megamonas,Barnesiella,Dialister,Megasphaera,[Ruminococcus]＿torques＿group and Fusobacterium in ASD group was higher than that in TD group(P < 0.05).Megamonas,Dialister,Megasphaera,Peptostreptococcaceae,Barnesiella,[Ruminococcus]＿torques＿group and Catenibacterium can be used as biomarkers of ASD group,while Lachnospiraceae,Peptococcaceae,Saccharimonadaceae,TM7 x,Allisonella,Paraprevotella,Lactobacillales＿g＿P5D1＿392and Saccharimonadales can be used as biomarkers of TD group.There was no significant difference in the prediction of phenotypic characteristics of gut microbiota between the two groups.The abundance of metabolic functions such as tryptophan degradation,glutamate degradation and butyrate synthesis of gut microbiota in ASD group was lower than that in TD group(P < 0.05),while the abundance of GABA degradation function in TD group was higher than that in TD group.Conclusions There was no significant difference in alpha diversity of gut microbiota between ASD and TD children.There was no significant difference in species distribution between the two groups at phylum and class level,but the species composition varies at the order,family and genus levels.Two groups of samples can be more accurately distinguished by the characteristics of bacteria at the genus level such as Megamonas,Subdoligranulum and Dialister.The phenotypic characteristics of gut microbiota in two groups of children were not significantly different,but there were significant differences in the metabolic functions of the microbiota.