Altered blood microbiome in patients with HCV-related decompensated cirrhosis

Background Altered bacterial translocation is associated with transitioning from compensated to decompensated cirrhosis. Thus, we aimed to study differences in the blood microbiome of HCV-infected patients with and without hepatic decompensation. Methods We conducted a cross-sectional study in patients with advanced HCV-related cirrhosis with or without human immunodeficiency virus (HIV) infection (n=88). MiSeq Illumina technology for bacterial 16S rRNA sequencing was used. Non-targeted metabolomics was performed by GC-MS and LC-MS ESI+ and ESI-. Results Patients with decompensated cirrhosis had lower levels of richness (Chao1), and alpha diversity (Shannon and Simpson indexes) at phylum level, than patients without decompensation. Likewise, we observed significant differences in beta diversity between groups at phylum, class and order levels, being lower in decompensated cirrhotic patients. Higher relative abundance of Proteobacteria (Fold Change (FC)=1.54, p=0.012), Alphaproteobacteria (FC=1.57, p=0.016) and Sphingomonadales (FC=1.61, p=0.050) were significantly associated with hepatic decompensation. The phylum Proteobacteria was positively correlated with ethanolamine and oleic acid (p=0.005 and p=0.004, respectively) and negatively with p-cresol (p=0.006). In addition, the order Sphingomonadales was also negatively correlated with p-cresol (p=0.001). Conclusions Blood microbial diversity was significantly decreased in patients with decompensated cirrhosis, who presented an enrichment of Proteobacteria, Alphaproteobacteria, and Sphingomonadales, compared to patients with compensated cirrhosis. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This study was supported by grants from Instituto de Salud Carlos III (ISCIII; grant numbers CP17CIII/00007, PI18CIII/00028 and PI21CIII/00033 to MAJS, PI17/00657 and PI20/00474 to JB, PI17/00903 and PI20/00507 to JGG, and PI17CIII/00003 and PI20CIII/00004 to SR) and Ministerio de Ciencia e Innovacion (PID2021-126781OB-I00 funded by MCIN/AEI/10.13039/501100011033 and by "ERDF A way of making Europe" to AFR). The study was also funded by CIBER - Consorcio Centro de Investigacion Biomedica en Red - (CB 2021; CB21/13/00044), Instituto de Salud Carlos III, Ministerio de Ciencia e Innovacion and Union Europea - NextGenerationEU. CB and DR acknowledge funding from the Ministerio de Ciencia, Innovacion y Universidades (RTI2018-095166-B-I00). MAJS and MR are Miguel Servet researchers supported and funded by ISCIII (grant numbers: CP17CIII/00007 to MAJS and CP19CIII/00002 to MR). ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The study received the approval of the Research Ethics Committee of the Instituto de Salud Carlos III (CEI42\_2020, CEI41\_2014) and was carried out following the Declaration of Helsinki. All participants of the study gave their written informed consent. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors. The raw sequences are publicly available at the European Nucleotide Archive repository (ENA; ) under the accession number PRJEB65371 * aAMR : Adjusted arithmetic mean ratio AMR : Arithmetic mean ratio ART : Antiretroviral therapy CTP : Child-Turcotte-Pugh ESI : Electrospray ionization FC : Fold Change FDR : False discovery ratio GC-MS : Gas chromatography-mass spectrometry GLM : Generalized linear model HCC : Hepatocellular carcinoma HCV : Hepatitis C virus HIV : Human immunodeficiency virus HVPG : Hepatic venous pressure gradient INR : International normalized ratio LC-MS : Liquid chromatography-mass spectrometry MANOVA : Multivariate analysis of variance OTU : Operative taxonomic Unit PCoA : Principal coordinates analysis PCR : Polymerase chain reaction