Mouth Bacteria Predicts Chronic Liver Disease Risk, Study Reveals

Each year, more than two million people die from advanced chronic liver disease (ACLD).

In the study, published in the journal Nature Microbiology, the researchers analysed bacterial populations in saliva and stool samples from 86 patients.

The team from the Technical University of Munich in Germany found that both the gut and oral microbiome undergo significant changes as liver disease worsens, where changes to the oral microbiome were already detectable at earlier disease stages.

In healthy individuals, bacterial communities differ substantially between body sites.

But, in patients with liver disease, oral and gut microbiomes became increasingly similar as the disease progressed, and nearly identical bacterial strains were recovered from the mouths and guts of patients.

"These strains are typically found in the mouth and are rarely present in the healthy gut. However, we observed increases in the absolute abundances of these oral bacteria in patients with advanced chronic liver disease," said Melanie Schirmer, Professor of Translational Microbiome Data Integration at TUM.

"This strongly suggests that these bacteria translocate from the mouth and colonise the gut," Schirmer added.

Further, the team identified several oral bacterial species that colonised patients' guts.

They also found evidence that higher levels of these bacteria in stool samples were associated with damage to the intestinal barrier.

Gene analysis showed that these bacteria carry genes encoding collagen-degradation enzymes.

The team confirmed these enzymes were active by testing isolated bacteria from stool samples and synthesizing the enzyme.

"Collagen breakdown can compromise the gut barrier, potentially allowing bacteria and bacterial products to reach other organs, such as the liver. We believe this may worsen the disease," explained Aurelie Cenier, a doctoral researcher and co-first author.

"Our findings open potential new therapeutic strategies for people with advanced chronic liver disease. Protecting or restoring the gut barrier could help slow disease progression. Targeting the oral microbiome offers a way to positively influence the course of the disease and prevent clinical complications," added Dr. Vishal Patel from King's College London.

- IANS