Blood Microbiome Profile in CKD : A Pilot Study Original paper

What was studied?

This pilot study investigated the blood microbiome profile in chronic kidney disease (CKD), focusing on how circulating microbial DNA differs between CKD patients and healthy individuals. Because the blood microbiome profile in CKD may reflect gut-blood barrier dysfunction and systemic inflammation, the study examined both the quantity and composition of bacterial DNA in buffy coat samples using quantitative 16S PCR and 16S targeted metagenomic sequencing. The aim was to characterize diversity, taxonomic patterns, and associations between microbial signatures and kidney function. This work helps clarify whether altered microbial communities in the bloodstream correspond to CKD severity and known dysbiosis-related inflammatory pathways.

Who was studied?

The study included 20 adults with nondiabetic CKD and 20 healthy controls. Participants in the CKD group represented a range of reduced kidney function, enabling analysis of microbiome shifts along gradients of glomerular filtration rate (GFR). All samples were collected in a cross-sectional design, and no participants had diabetes, which reduced potential confounding from metabolic disease. Healthy controls were matched to represent a baseline circulating microbiome for comparison. The intention was to assess microbiome patterns attributable to CKD physiology rather than unrelated comorbidities.

Most important findings

The analysis revealed significant qualitative differences in circulating microbial DNA. CKD patients exhibited lower α diversity, indicated by a reduced Chao1 index (127±18 vs. 145±31), suggesting diminished richness of detectable blood-associated taxa. A total of 22 operational taxonomic units (OTUs) differed significantly between groups. The CKD blood microbiome was enriched in Proteobacteria, especially Gammaproteobacteria, with overrepresentation of Enterobacteriaceae and Pseudomonadaceae—families commonly linked to gut permeability, systemic inflammation, and pathobiont expansion in dysbiosis. Although total 16S copy numbers did not differ between CKD and controls, the microbial composition shifted toward these inflammation-associated taxa. Importantly, GFR correlated inversely with Proteobacteria abundance (r = −0.54), implying that worsening kidney function accompanies escalating dysbiosis signatures in circulating blood. These findings align with research showing that CKD-associated gut barrier dysfunction promotes translocation of Proteobacteria-rich communities, potentially contributing to endotoxemia and chronic inflammation.

Key implications

The study underscores that CKD is associated not only with gut dysbiosis but also with distinct alterations in the circulating microbiome. Reduced α diversity and increased Proteobacteria-rich taxa suggest systemic microbial imbalance that parallels disease severity. These microbial patterns may serve as biomarkers for CKD progression or inflammatory burden and reinforce the pathogenic link between gut permeability, bacterial translocation, and renal decline. Although pilot in scale, the work provides strong rationale for integrating blood microbiome signatures into broader microbiome–kidney interaction research. Future studies with larger cohorts could validate these microbial markers and explore therapeutic interventions targeting gut–blood microbial dynamics to alleviate CKD-related inflammation.

Citation

Shah NB, Allegretti AS, Nigwekar SU, et al. Blood microbiome profile in CKD: a pilot study. Clin J Am Soc Nephrol. 2019;14(5):692-701. doi:10.2215/CJN.12161018