Alterations Of Intestinal Microbiota In Patients With End-stage Renal Diseases Undergoing Different Dialysis Modalities

Objective:1.To characterize the structural and functional diversity of gut microbiome in patients with end-stage renal disease(ESRD)undergoing two different dialysis modalities of hemodialysis(HD)and peritoneal dialysis(PD),so as to develop new microbial-targeted drugs to delay the disease progression of patients.2.To investigate the expression of serum zonulin in ESRD dialysis patients and its influencing factors,thus to judge whether the intestinal flora disorders are related to the zonulin-mediated intestinal permeability.Methods:1.The 16 S rRNA gene V3-V4 region of 20 ESRD HD patients,10 ESRD PD patients and 17 healthy adult fecal microbial genomes was amplified and high-throughput sequenced by 16 S rRNA sequencing approach on the Illumina MiSeq platform.Sequences from each sample were quality controlled using the Qiime2 analysis platform to obtain the Operational Taxonomic Unit(OTU),then annotated with taxonomy information against Greengene database.The composition of the microbiota and the Alpha and Beta diversity of the community were analyzed based on OTU.Meanwhile,Linear Discriminant Analysis Effect Size(LEfse)was used to screen out the species with significant difference between groups.Finally,the potential functional profiles of the microbial communities ware predicted with the Phylogenetic Investigation of Communities by Reconstruction of Unobserved States(PICURSt)on each group.2.Enzyme-Linked Immunosorbent Assay(ELISA)was used to detect the serum zonulin of each group,and the possible influencing factors were analyzed as well.Results:1.Most of the intestinal flora in HD,PD and HC groups belonged to the Firmicutes,Bacteroidetes,Proteobacteria at the phylum level,accounting for 96.10%,95.35% and 97.93%,respectively.Compared with the HC and PD group,the HD group showed a significantly lower abundance Bacteroidetes and higher abundance of Firmicutes;while the relative abundance of each phylum in PD group was similar to the HC group,with no significant difference were detected.2.The results of Alpha-diversity in the gut microbiota of each group showed that,the faith_pd and observed_otus index of the HD and PD group were significantly decreased compared with HC group,while no significant difference was detected between HD and PD group;In addition,no significant difference was shown in shannon index among the 3 groups.3.The beta-diversity of the gut microbiota among the group was evaluated based on the unweighted_unifrac distance,the results showed that the HC and HD group,HC and PD group were significantly different,while there was no significant difference between HD and PD group.4.LEfSe analysis showed that a difference of 20 phylotypes was observed in the 3 group at the genus level,and the area under the ROC curve(AUC)was used to explore the ability of the bacteria to differentiate from other groups.Firmicutes achieved the highest AUC in the HD group(AUC = 0.763;95% CI: 0.614-0.912;P = 0.002);while Fusobacterium achieved the highest AUC in the PD group(AUC = 0.811;95% CI: 0.690-0.931;P = 0.003).5.Gut microbial predicted function showed that,there were significant differences between HD group and HC,PD group.HD group decreased significantly in the functions about Carbon fixation pathways in prokaryotes,Chaperones and folding catalysts,Energy metabolism,Oxidative phosphorylation,Peptidases,Purine metabolism,Pyrimidine metabolism,Ribosome,Transcription machinery and so on,while ABC transporter,Glycolysis/Gluconeogenesis,Transcription factors and Transporters and so on,significantly enhanced.Compared with HC group,the PD group showed no significant difference in most known microorganisms functions except the overrepresented in Cellular Processes and Signaling and Metabolism.6.The related factors affecting the diversity index of intestinal flora showed that,in the HC group,the observed_otus index was significantly negatively correlated with the serum albumin(ALB),but was not significantly correlated with the age,Body Mass Index(BMI),total cholesterol(TC),triglyceride(TG)and hemoglobin(Hb);in the HD and PD groups,the observed_otus index showed no significant correlation with the above indicators.7.There was no significant difference in serum zonulin levels among the groups.The results of zonulin-related influencing factors showed that zonulin was positively correlated with age and negatively correlated with ALB in HC group,while no significant correlation was observed in the HD group,nor the PD group.Conclusions:1.Both HD and PD renal replacement treatments lead to a decrease in intestinal microbial diversity,but they have different effects on the major microbial communities.HD is more likely to change the construction and function of intestinal microbial than PD,it is suggested that PD mode of ESRD patients is superior to HD mode on the effect of intestinal flora in the situation of no curative effect affected.2.Changes in intestinal flora in ESRD dialysis patients cannot be determined to be associated with zonulin-mediated intestinal permeability yet.