Flos Abelmoschus Manihot Extract Attenuates DSS-Induced Colitis By Regulating Gut Microbiota And Th17/Treg Balance

Background:Ulcerative colitis(UC)is one type of inflammatory bowel disease(IBD)which characterized by chronic and repeated episodes enteropatia.The cause of UC is still unclear.The symptoms of UC are diarrhea,abdominal pain and bloody stools.Repeated episodes of UC may lead to the occurrence of colon cancer.A wide range of bacteria-based microorganisms resident in the human intestines,which are collectively referred to as intestinal microbiota.Research shows that intestinal microbiota is involved in the immune regulation and host defense function of the body,and the disorder of intestinal microbiota can lead to intestinal immune disorder in UC patients,thus aggravating the process of enteritis.Abelmoschus Manihot(L.)belongs to the family of Malvaceae,which can clearing heat and toxic and reducing swell in the traditional Chinese medicine(TCM)Abelmoschus manihot(L.)is clinically used to treat inflammatory diseases.Previous studies have found that Abelmoschus manihot(AM)has a significant effect on ulcerative colonic inflammation,but the mechanism of action is still unclear.Objective:To investigate the therapeutic effect of Abelmoschus manihot(AM)on DSS-induced UC mice and its specific mechanismMethods:BALB/c mice(6-8weeks,male)were randomly divided into control group,model group and different doses of AM treatment group,and the UC mice model of control group and model group were established by 3.5%DSS.The mice were sacrificed after 7 days of different doses of AM gavage treatment.Observed the body weight and disease activity index(DAI),pathological changes of the colon,and detected the expression of colonic inflammatory factors,chemokines and mucosal integrity molecules by RT-PCR,detect the protein expression of inflammation-related signaling pathways by Western Blot,detect the proportion of immune cells such as neutrophils,macrophages,Th17 and Tregs by FACS,16S Ribosomal RNA sequencing technology was used to analysis the structural change of gut microbiota and the metabolism of fecal were analyzed by GC-MS,the cohousing experiment was also performance and further cell experiments were performance to research the specific mechanisms of AM.Results:The mice showed obviously ulcerative colitis symptoms after DSS induction,the body weight were significantly reduced and DAI score obviously increased in mice.The level of inflammatory factors(IL-6,TNF-?,etc.)and chemokines(CXCL1,CXCL2,etc.)in the colon tissue were significantly increased,the integrity of intestinal mucosal was impaired,and immune cells Th17/Treg were imbalanced,Neutrophils,Macrophages were significantly increased.The balance of intestinal microbiota was also broken after DSS induction which shows increased proportion of Bacteroides and decreased Lachnospiraceae and Firmicutes.The content of butyric acid and acetic acid in fecal metabolites also decreased significantly.While after the treatment of different doses of AM,the symptoms of intestinal inflammation were significantly improved,DAI score was obviously decreased.The expression of cytokines and mucosal integrity molecules were decreased The imbalance of Th17/Treg and abnormally elevated Neutrophils and Macrophages were significantly improved.The relative abundance of significantly altered gut microbiota were tending to be normal and the content of butyric acid and acetic acid in fecal metabolites was increased.Our co-housing experiment suggested that the intestinal microbiota has a significant effect on UC progressing.The further experiments suggested that PPAR? pathway was involved in AM-mediated regulation of Th17/Treg balance.Conclusions:AM attenuates DSS-induced colitis by regulating gut microbiota and Th17/Treg balance,and the butyric acid-activated PPAR? pathway may be the target of AM.