| ObjectiveUlcerative colitis(UC)is a common but refractory inflammatory bowel disease(IBD)in modern times.Epidemiologic studies have shown that incidence rate of UC keeps increasing worldwide,as well as in China.The clinical symptoms of UC mainly characterize as abdominal pain,diarrhea and colorectal bleeding.In microscopic view,colonic mucous injuries and inflammation are commonly found in disease region.However,the pathogenesis of UC remains unknown.It is urgent to speed up the investigation of UC pathogenesis and finding effective therapies for it.Gallic acid(GA)is a natural-derived polyphenol existed in many plants and fruits.Researchers found GA equips with multiple bioactivities,such as anti-oxidation,anti-tumor,anti-bacteria and anti-inflammation.In fact,GA and its derivatives carry can exactly attenuate UC.However,the mechanism remains unknown.In this study,we investigated the therapeutic effect of GA in treating UC from the perspective of gut microbiota.With the help of 1H-NMR based metabolomics,maybe we can understand how GA works on UC.Methods1.Establishment of UC animal model and preliminary evaluation of GA treament4%(W/V)DSS solution were used to induce UC in rats.And GA(6mg/kg)was simultaneous rectally administrated every day until the end of the experiment.During the experiment,it is necessary to observe and record the physical and mental status of rats.Urine and feces samples should be collected in time at the end of experiment.Comprehensive assessment was performed to evaluate UC modelling and GA treatment through detecting various biochemical index,including DAI scoring,length of colon,histopathlogical examination of HE staining colon tissue,SOD,MDA and several inflammatory cytokines2.Analysis on microbiota16S rRNA sequencing was conducted on feces samples and data were analyzed on some bioinformatic processing platform like Illumina Miseq.Preliminary impact of UC or GA treatment could be firstly achieved from α and β diversities,which can show us the similarity between individuals and groups.The advanced analysis performed on relative abundance of microbiota under different taxonomic levels was helpfule in screening out potential micriobiota that closely related with UC or GA treatement.Microbial metabolic functions were alaso predicted based on the existed composition.4.Metabonomic analysis1H-NMR based non-target metabolomics were used in analyzing metabolites existed in urine and feces,combining with multivariate analysis in order to screen out the potential biomarkers.Results1.The pathological examination displayed that UC symptoms were greatly attenuated after GA treatment,showing as decreasing DAI score and histological score of colon tissue,as well as other attenuated biochemical index.2.Compared with control group,microbiota compositions in both DSS group ande GA group were greatly changed,but GA group shared higher similarity with control group than DSS group.The altered microbiota composition induced by DSS featured as the decrease of some beneficial bacteria(such as Lactobacillus,Prevotellaceae)and the increase of some pathological bacteria(most of bacteria in Proteobacteria phylum).The above condition was improved in GA treatment group and developed towards to control group,reminding us that GA can somehow attenuate dysbiosis in UC.The thrived genus in GA group like bacteroides and rc4-4 were regardeda as the potential marker genus that closely linked with GA treatment.The predicted functions revealed that GA was powerful in increasing gluco-related metabolism,bile acids(BAs)-related metabolism while amino acids-related metabolism decreased.3.Metabolic data further revealed that UC or GA-induced metabolic changes mainly focused in carbohydrates metabolism and amino acid metabolism while lipid metabolism and nucleic acid metabolism suffered from less impact.Particularly,changes in DSS group were featured as increase of short chain fatty acid(SCFAs)and amino acid,as well as the decrease of tricrboxylic cid cycle(TCA)-related and nucleic acid-related metabolites.After GA intervention,some carbohydrates increased in feces and some harmful amino acidderived metabolites were decreased.ConclusionThese findings demonstrated a GA-induced holistically alterations in metabolic and bacterial profiles in DSS-induced colitis,providing new insight to the attenuation of GA in UC. |
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