Metabolomics Study Of Inflammatory Bowel Disease Based On Chromatography Coupled To Mass Spectrometry

Inflammatory bowel disease(IBD),including Crohn’s disease(CD)and ulcerative colitis(UC),is a kind of systemic disease and can violate the whole digestive tract associated with immune abnormalities.It has a serious impact on the quality of people’s life.However,the pathogenesis of IBD is not clear.Biological system makes responses with multi-level,multi organ and multi tissue when it suffers from external stimuli or disturbance,leading to the level changes of metabolites.Metabolomics is to study the level changes of low-molecular-weight metabolites(molecular weight less than 1000)so as to facilitate the screen of potential biomarkers and to provide a new insight to the pathogenesis of diseases.In this paper,the metabolomic methods based on gas chromatography-mass spectrometry were established.We optimized the pretreatment methods of serum samples,including the proportion of acetonitrile for protein precipitation and the temperature of derivatization reaction.Next,we conducted the metabolomic study of inflammatory bowel disease by using the dextran sulfate sodium(DSS)induced IBD mouse model.The metabolic profiles of the normal group and IBD mouse were examined with the assistance of the statistical methods.From these,the discriminating metabolites such as glycine,serine,threonine,urea,uric acid,purine,malic acid,isocitric acid and glucose were screened;metabolic pathway analysis revealed that urea cycle,amino acid metabolism,purine metabolism,the citric acid cycle and glycolysis were possibly related to IBD.Also,our previous study found that peroxisome proliferator-activated receptor α(PPARα)can aggravate the symptoms of IBD.So we further studied the metabolomic characteristics of IBD mice after intervention with fenofibrate(PPARα agonist).It turned out that the up/down-regulation level changes of the above metabolites were further potentiated following fenofibrate treatment.With the aid of the quantitative PCR analysis and metabolic pathway analysis,serine-glycine-threonine metabolic pathway,urea cycle,tricarboxylic acid cycle and the key enzyme expression were changed.The above work provides new clues for exploring the pathogenesis of IBD.At present,most drugs for the treatment of IBD exist adverse reactions and are not suitable for long-term treatment.Hence,it is urgent to research and develop new drugs for IBD.Celastrol has shown anti-inflammatory effect,but the mechanism is not clear.Therefore,we developed lipidomics study of celastrol for the treatment of IBD using UPLC-MS technique to explore the mechanism of its efficacy.Based on IBD model induced by DSS,we evaluated the efficacy of celastrol for the treatment of IBD and found that celastrol can significantly relieve the symptoms of IBD.Lipidomics study found that the normal group,IBD model group,the positive control drug(mesalazine)treatment group and celastrol treatment group were well separated;By the quantitative analysis compared wih the normal group,it revealed that sphingomyelins(SM)and ceramides(CER)were significantly increased in IBD mice,and were then effectively reversed following celastrol treatment.This showed that celastrol may play the anti-colitis effect through the intervention of sphingolipid metabolism.The above results provide the basis for elucidating the mechanism of celastrol for the treatment of IBD.