Profiling Of The Gut Microbiome In Infants With Biliary Atresia

Background:Biliary atresia(BA)is an infant progressive fibrosing obliterative cholangiopathy which results in cholestasis and rapidly progressive biliary cirrhosis.BA is a devastating disease;if no therapy is implemented,influenced infants evolve rapidly into end-stage liver disease within 2 years of age.The Kasai portoenterostomy surgical procedure is currently used as a first-line treatment to restore bile flow in infants with BA.Although early diagnosis and successful surgical treatment may re-establish biliary flow to the intestine,progression to end-stage liver disease occurs in 75%–80% of patients by adult age.BA is a common indication of paediatric liver transplantation worldwide.However,the treatment cost of liver transplantation is high,and immunosuppressants need to be taken for life,which not only causes a heavy burden on the children's family and society,but also seriously affects the recognition and credibility of the family members to the pediatric surgeons.Therefore,the research on BA has important social significance.The etiology of BA is still unknown.In recent years,its etiology research mainly focuses on immunology.The abnormal immune response caused by excessive activation of Th1 cells and imbalance of Th17 cells / Treg cells may play an important role in BA progressive inflammation.After long-term research,some scholars have confirmed that intestinal microorganisms can regulate immune cells such as Th1,Th17 and Treg cells.Once the flora stability of this site is broken,it will lead to a series of diseases,such as inflammatory bowel disease(IBD),rheumatoid arthritis(RA),systemic lupus erythematosus(SLE),Behcet's disease(BD)and multiple sclerosis(MS).Although the epidemiology,pathophysiology and therapeutics of BA are being deeply studied,the interaction between BA and gut microbiome has received little attention.In the first part,We employed 16 S r RNA high-throughput gene sequencing,Illumina Nova Seq,to analyse stool samples from 43 BA patients and 22 healthy individuals.3150811 sequences of V3-V4 region of 16 S r RNA gene with complete information were obtained,and then these sequences were divided into 1034 operational taxonomic units(OTUs).Generally speaking,the alpha diversity of gut microbiota in the BA patients was more profound than that in healthy controls.Two phyla,Firmicutes and Proteobacteria,were enriched in BA patients,whereas Actinobacteria and Bacteroidetes were enriched in healthy individuals.At the genus level,the abundance of some potential pathogens,including Streptococcus,Klebsiella and Haemophilus,were increased in BA patients,when Bifidobacterium,Bacteroides and Lactobacillus were drastically deacreased.This study provides a comprehensive dissection of the prominent phyla and genera discriminating BA patients from healthy individuals.A possible microbiome remodelling in BA has been postulated,suggesting that the unique gut microbiota might be correlated with the dramatic reduction in intestinal bile acids and that the digestion and protein synthesis are impaired as consequence in the BA patients.In the second part,the gut microbiome of BA liver transplantation recipients was studied.A total of 46 fecal samples were collected from the BA pre-liver transplantation group(n=12),BA post-liver transplantation group(n=12)and the healthy control group(n=22).Then,fecal genomic DNA was extracted.A total of 2156108 high qualified 16 s r RNA V3-V4 sequences and 729 OTUs were obtained by 16 S r RNA gene high-throughput sequencing.The results showed that the intestinal microorganisms of the three groups belonged to 10 phylums,including Proteobacteria,Actinobacteria,Bacteroidetes,Firmicutes,fusobacteria,Epsilonb-acteraeota,Cyanobacteria,Verrucomicrobia,Acidobacteria,Patescibacteria.Among them,Proteobacteria,Actinobacteria,Bacteroidetes and Firmicutes account for approximate 98% of all the bacteria from these specimens.In this study,the abundance of Actinobacteria in feces was decreased in pre-LT group compared with control group;The abundance of Firmicutes increased significantly,and Proteobacteria did not change significantly.Compared with BA pre-LT group,the abundance of Firmicutes in feces from BA post-LT group increased,while the abundance of Actinobacteria and Bacteroidetes decreased significantly.There were statistically differences in gut microbiome between control,pre-LT and post-LT group.Through the study of gut microbiome in patients with biliary atresia(BA),Illumina Nova sequencing was used to describe the structure and abundance of gut microbiome in BA patients for the first time,and compared with the healthy individuals,so as to provide important reference data for further study on the relationship between gut microbiome and host metabolism,immune regulation and relative diseases.In addition,by comparing the changes of gut microbiome before and after liver transplantation in BA patients,this study preliminarily reveals the effects of special factors such as liver transplantation and immunosuppressive therapy on gut microbiome,so as to provide an important evidences for further research.