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Liver fibrosis linked to blood microbiota in obesity

Blood microbiota dysbiosis and liver fibrosis existed concomitantly in patients with obesity, according to published findings.

“We have shown in an extensively phenotyped cohort, for the first time, a relationship between liver fibrosis in patients with severe obesity and both blood bacterial burden and blood microbiota profile,” Benjamin Lelouvier, PhD, group leader of molecular and cellular biology at Vaiomer SAS in France, told Healio.com/Hepatology. “The 16S rDNA concentration was significantly higher in patients with liver fibrosis whereas the diversity indices were lower for all taxonomic levels considered. We found specific differences in the proportion of specific bacterial taxa in both blood and feces that correlate with the presence of liver fibrosis, thus defining a specific signature of the liver disease.”

Benjamin Lelouvier

Lelouvier and colleagues divided 121 patients with liver fibrosis and obesity into two groups. The discovery cohort consisted of 50 patients who were Spanish, most of whom had fecal, plasma and buffy coat samples available. The remaining patients — Italians who had fecal and whole blood samples available — were placed in a validation cohort. A patient’s obesity was determined by the severity of their nonalcoholic fatty liver disease.

The discovery cohort had plasma bile acid contents analyzed. Both cohorts had blood bacterial DNA qualitatively examined using functional metagenome prediction and 16S rDNA targeted metagenomic sequencing, and quantitatively examined using 16S rDNA qPCR.

In the discovery cohort, researchers found:

• a relationship between 16S rDNA concentration and liver fibrosis; however, a distinct bacterial taxa signature could not be verified;
• significantly higher 16S rDNA concentration;
• primary/secondary bile acid ratios decreased;
• distinct versions of fecal microbiota taxa and functions closely connected to liver fibrosis; and
• less blood bacterial 16S rDNA variety.

“The results presented here suggest that blood bacterial DNA measured by qPCR could be employed effectively for the diagnosis of the presence or the absence of liver fibrosis in patients with severe obesity. In the latter situation, patients would avoid un-needed liver biopsy,” the researchers wrote.

A fecal and blood bacterial profile associated with fibrosis was detected in the discovery cohort but not the validation one, suggesting a relationship between the environment and groups of bacteria distinct to the geographic area on liver fibrosis in patients who have obesity. A relationship between liver cirrhosis, reduction of serum secondary/primary bile acid ratio and modified gut microbiota was observed in both cohorts, according to researchers.

“Blood microbiota analysis provides biomarkers for the early detection of liver fibrosis in patients with severe obesity,” Lelouvier told Healio.com/Hepatology. “Bacterial communities present in blood and tissue could play a causal role in liver fibrosis in patients with severe obesity and be targeted by therapeutic strategies.” – by Janel Miller

Disclosures: The researchers report no relevant financial disclosures.