Study On Gut Microbiota And Tryptophan Metabolites In Metabolism-related Fatty Liver Disease

Objective:To investigate the characteristic gut dysbiosis and the changes in fecal tryptophan metabolites in patients with metabolic-associated fatty liver disease（MAFLD）.To explore the possible mechanism of gut microbiota and tryptophan metabolism on the occurrence and development of MAFLD,and to provide theoretical basis for the diagnosis and treatment of intestinal flora in MAFLD.Methods:A total of 90 MAFLD patients were recruited in the study,after rigorous screening,26 MAFLD patients and 22 age-and sex-matched healthy controls（HC）were enrolled in the study.All patients were admitted to the Sichuan Provincial People’s Hospital from September 2020 to September 2021.Clinical data,blood specimens and stool samples were collected from all subjects.Fecal samples were subjected to microbiome（High-throughput sequencing）and metabolome analyses.Sequencing data of 16 S r DNA was performed using Illumina Nova Seq platform,tryptophan and metabolites in feces analysis was measured by Ultra High Performance Liquid Chromatography/Mass Spectrometry.To explore whether there are differences in tryptophan metabolism between MAFLD group and HC.And screened different metabolite profiles,analyzed the relationship of tryptophan metabolites with gut microbiota in patients with MAFLD.Results:1.There were differences in the distribution of the gut microbiome between MAFLD patients and healthy controls.At the phylum level,Bacteroidetes,Fusobacteria,Verrucomicrobiota were significantly enriched in patients with MAFLD,Actinobacteriota,Firmicutes,Actinobacteriota were significantly decreased in patients with MAFLD.At the level of genus taxonomy,Bifidobacterium,Escherichia-Shigella,Roseburia,Subdoligranulum were significantly decreased in MAFLD patients.Faecalibacterium,Prevotella,Lachnospira,Megamonas were significantly enriched in the MAFLD group.2.Significant difference analysis found that the abundance of g＿＿UCG-002,g＿＿Lachnoclostridium and g＿＿Clostridium＿sensu＿stricto＿6 species were significantly higher in patients with MAFLD than in healthy adults,while the abundance of g＿＿CAG-352,g＿＿Alistipes,g＿＿Christensenellaceae＿R-7＿group,o＿＿Christensenellales,f＿＿Christensenellaceae,g＿＿Ruminococcus,c＿＿Actinobacteria,f＿＿Bifidobacteriaceae,o＿＿Bifidobacteriales,g＿＿Bifidobacterium,g＿＿Ruminococcus,g＿＿Escherichia-Shigella were significantly lower than those in healthy controls.3.The fecel tryptophan metabolism in MAFLD patients and healthy controls were different.The concentrations of tryptophan metabolites such as indole-3-aldehyde,indole-3-acetic acid in MAFLD patients were significantly lower than those in healthy controls（P<0.05）.And 3-Hydroxykynurenine,5-methoxy-indoleacetic acid,indole-3-acetylalanine were significantly higher than those in HCs（P < 0.05）.4.Tryptophan metabolites（IAld and IAA）were positively related to g＿＿Alistipes,g＿＿Christensenellaceae＿R-7＿group,g＿＿Ruminococcaceae＿unclassified,g＿＿UCG-002（P < 0.05）.IAld and IAA were negatively correlated with g＿＿Lachnoclostridium（P <0.05）.Conclusions:Dysregulation of the gut microflora and altered constitution of tryptophan metabolites in MAFLD patients.Fecal tryptophan metabolites are closely related to the gut microbiota in patients with MAFLD,effects of the microbiota on the occurrence and development of MAFLD may be related to the change of tryptophan metabolites.