Metabolomic Study Of Sepsis Based On ¹³C Isotope Labeling

Objective:This thesis combined stable isotope labeling with metabolomics,based on nuclear magnetic resonance spectroscopy,to explore the metabolic dynamic trends of sepsis in depth,search for metabolic markers of sepsis,which help to construct a predictive model based on metabolome.Methods:SD rats were used for this experiment.They were divided into six groups with four rats per group according to computer randomization method.Then,the sepsis and control models were established after adaptation feeding for five days.Blood samples were involved via the abdominal aorta at 6h,10h,24h,48h,and 72h after successful modeling.Then,these blood samples were analyzed by proton-1 nuclear magnetic resonance（¹H-NMR）and carbon-13 nuclear magnetic resonance(¹³C-NMR).Serum metabolomics analysis was conducted by using software Chenomx9.0,Mest Renova14,and Metaboanalyst5.0.Principal component analysis（PCA）and partial least squares discriminant analysis（PLS-DA）were used for pattern recognition.Differential metabolites between the groups were screened,combining fold change（FC）>2 or FC<0.5,P<0.05,and variable important in projection（VIP）value>1.Then,related metabolic pathways were found.Results:This thesis found that the mortality of septic rats was 25%during the 24-48h and 42%during the 48-72h.Based on an untargeted ¹H-NMR metabolomics study,nineteen differential metabolites involving twenty-one metabolic pathways were identified by comparing metabolic differences between septic rats established by cecum ligation and puncture（CLP）and normal rats.Twenty-seven differential metabolites involving sixteen metabolic pathways were found between septic rats and non-septic rats.A total of thirty-nine differential metabolites were identified by metabolic differences between septic rats at different time periods.Combined with a targeted ¹³C-NMR study,sixteen metabolites involving nineteen metabolic pathways,changing with the occurrence and progression of sepsis,were found.Conclusion:This thesis conducted untargeted and targeted metabolomics analysis of septic rats by using stable isotope tracing combined with NMR,explored the metabolic changes during the occurrence and progression of sepsis,and identified the metabolite profile and related metabolic pathways in septic rats.