Metagenomic And Metabolomic Analyses Unveil Dysbiosis Of Gut Microbiota In Chronic Heart Failure Patients

Objectives Chronic heart failure(CHF)is an end-stage syndrome of many cardiovascular diseases.Gut's roles in CHF have been discussed for years.The classic recognition of that included the intestinal hypoperfusion,barrier dysfunction,bacteria and endotoxin translocation.Recent studies suggested trimethylamine N-oxide,a gut microbes-dependent metabolite,as a biomarker for CHF,and that more pathogenic bacteria could be cultivated from CHF patients' faecal samples.However,changes in microbial metabolites could only be indirect evidence for gut microbiota dysbiosis,while about 80%of gut microbes could not be cultured yet.In view of this,direct evidence for gut microbiota dysbiosis in CHF patients was still lacking.The present study aimed to provide direct evidence and comprehensive understanding of gut microbiota dysbiosis in CHF by using metagenomic analyses and metabolomic analyses.Methods In the present study,we consecutively recruited 53 CHF(ischaemic cardiomyopathy,n = 29;dilated cardiomyopathy,n =24)patients who were admitted to Fuwai Hospital(n = 37),Chaoyang Hospital(n = 9)and Pingjin Hospital(n = 7)and 41 individuals from Kailuan Community as controls.The demographic and clinical characteristics of subjects were collected.Metagenomic analyses of faecal samples,metabolomic analyses of faecal and plasma samples collected from subjects were performed,in combination of the combining analyses of metagenomic and metabolomic data.Results First,the beta-diversity analysis based on Bray Curtis distances showed that the structure of gut microbiota in CHF patients was significantly different from controls(F =5.66,p = 0.003,R2 = 0.0580),while quite similar between dilated cardiomyopathy-and ischaemic cardiomyopathy-induced CHF(F = 2.01,p = 0.101,R2 = 0.0380).Second,the co-occurrence network of marker co-abundance gene groups suggested that Faecalibacterium prausnitzii decrease and Ruminococcus gnavus increase were the essential characteristics in CHF patients' gut microbiota.Third,the functional annotations of the metagenome unveiled multiple significant functional shifts of the gut microbiota in CHF patients.Importantly,there existed an imbalance of gut microbes involved in the metabolism of protective metabolites such as butyrate and harmful metabolites such as trimethylamine N-oxide in CHF patients.Forth,the metabolic analyses based on liquid chromatography-mass spectrometry suggested that there existed significant differences in both the faecal and plasma metabolomic patterns between CHF patients and controls.Based on orthogonal partial least-squares discriminant analysis,multiple differentially enriched metabolites in both faecal and plasma samples between CHF and controls were identified.Importantly,an increase of cardiovascular harmful metabolites such as sphingosine 1-phosphate and a decrease of cardiovascular protective metabolites such as orotic acid in CHF patients were observed.Finally,combining analyses of metagenomic and metabolomic data,significant correlations between changes in certain metabolites and gut microbes were further identified.For example,decreased metabolites in CHF patients'faecal samples such as niacin,cinnamic acid and orotic acid were negatively correlated with CHF-enriched bacteria Veillonella,while high levels of sphingosine 1-phosphate in CHF patients' plasma samples were positively correlated with several CHF-enriched bacteria such as Veillonella and Streptococcus.Conclusions Based on metagenomic and metabolomic analyses,this present study unveiled distinct gut microbiota dysbiosis in CHF patients,and pinpointed the specific core bacteria imbalance and significant functional shifts in the gut microbiota of CHF patients,along with correlations between altered metabolic patterns and gut microbiota.These findings provided not only direct evidence to validate the hypothesis of gut microbiota dysbiosis in CHF patients,but also a comprehensive understanding of the correlation between CHF and gut microbiota dysbiosis,which is fundamental for further investigations on the interaction between gut microbiota and CHF.