Multi-Omics Study On The Gut Microbiota And Lipid Metabolism On Disease Severity Of Critically Ill Patients After Cardiovascular Surgery Combined With Cardiopulmonary Bypass

Objective:Organ failure after cardiovascular surgery combined with cardiopulmonary bypass are an important reason for increased postoperative mortality.Intestinal ischemia-reperfusion during cardiac surgery may cause bacterial translocation,lipid metabolism disturbances,and progression of critically ill.Postoperative unexplained fever with haemodynamically unstable symptoms exacerbates organ damage and inflammation,and is often diagnosed clinically as sepsis.In this study,we want to explore the microbiota and lipid changes on disease severity after cardiovascular surgery combined with cardiopulmonary bypass through multiomic stydies and postoperative clinical diagnosis of Sepsis.Methods:Part Ⅰ,We designed a prospective observational cohort study of patients undergoing cardiopulmonary bypass collecting stool samples one day before and within 48 to 72 hours after surgery.All stool samples were sequenced metagenomic to characterize the gut microbiome.Patients were subjected to intestinal clustering analysis combined with a random forest algorithm to screen for differential microorganisms.The correlation between differential microorganisms and organ damage,disease severity and prognosis was analyzed.Part II,in the exploration phase,a prospective observational case-control study of patients undergoing cardiopulmonary bypass surgery in cardiac surgery was designed.Patients diagnosed with sepsis 48-72 hours after surgery were included as the case group and non-sepsis patients were included as the control group.Plasma samples are collected the day before and within 48 to 72 hours after surgery.High-performance liquid chromatography coupled to tandem mass spectrometry was used to explore global lipidome changes in plasma samples.Combined with bioinformatics analysis and machine learning algorithms to further identify differential lipids.Differential lipid metabolism pathway enrichment analysis using the Kyoto Encyclopedia of Genes and Genomes(KEGG)database.The correlation between differential lipids and organ damage,disease severity and prognosis was analyzed.In the validation phase,critically ill patients after cardiopulmonary bypass were prospectively enrolled as a validation cohort to confirm the effect between lipid changes pre and postoperation and clinical diagnosis of sepsis.Results:In the first part,a total of 87 fecal samples were collected before and after surgery(54 preoperative and 33 postoperative),and two enterotypes were identified in metagegene sequencing intestinal microbial samples,namely enterotype Ⅰ and enterotypeⅡ.Patients undergoing cardiopulmonary bypass tended to switch their enterotypes to enterotype Ⅱ,with the proportion of samples in enterotype Ⅱ rising from 31.5%to 63.6%(p=6.7×10-3).Enterotype Ⅱ exhibited lower alpha-diversity(p=2.7×10-5).The abundance of three microorganisms(Citrobacter,Cronobacter and Pluralibacter)was higher in enterotype Ⅱ(p<0.05),and the abundance of these three microorganisms was correlated with the clinical APACHEⅡ.Score(Cronobacter,R=0.44,p<0.01;Citrobacter,R=0.42,p<0.01;Pluralibacter,R=0.27,p<0.01).In further subgroup analysis,this correlation was also present in the sepsis group(APACHEⅡ:Cronobacter,R=0.69,p<0.01;Citrobacter,R=0.73,p<0.01;Pluralibacter,R=0.53,p<0.01),and the abundance of three bacteria in the sepsis group was associated with length of ICU stay(ICU time:Cronobacter,R=0.6,p=0.01;Citrobacter,R=0.61,p<0.01;Pluralibacter,R=0.45,p=0.067).In the second part,a total of 60 cardiopulmonary bypass patients were enrolled in the lipidomics study and 120 plasma samples were collected.Patients were divided into sepsis and non-sepsis groups according to their manifestations of organ damage(SOFA score)and suspected infection after surgery.Compared with preoperative samples,95 features were upregulated(FC≥1.5,p<0.05)and 314 features were downregulated(FC≤0.67,p<0.05)in the postoperative samples."Autophagy"(FDR<0.01,p<0.01),"pathogenic Escherichia coli infection"(FDR=0.026,p<0.01)and"glycosylphosphatidylinositol-anchor biosynthesis"(FDR<0.01,p<0.01)pathways were significantly enriched in the KEGG database pathway enrichment analysis.A multistep machine learning framework further confirmed that there were significantly differences between two cholesterol esters(CE(18:0)and CE(16:0))and three fatty amides(oleamide,stearamide,palmitamide)(p<0.05).In the validation cohort,all three fatty amides were detected with significant increased postoperatively(p<0.05),but there was no significant difference between the sepsis and non-sepsis groups.Conclusion:In this study,high-throughput sequencing and multi-omics methods combining high-performance liquid chromatography coupled to tandem mass spectrometry were used to find that three intestinal bacteria(Cronobacter.Citrobacter and Pluralibacter)were associated with the severity of the condition in patients after cardiopulmonary bypass.Although the differences in lipid metabolism could explain the changes in disease severity after surgery,it was not further verified after subgroup analysis based on the clinical diagnosis of sepsis-3.0.These results provide a possible site for further study of the influence of microbiota and lipid metabolism changes on the degree of host disease,and provide directions for clinical transformation and precision therapy..