Bacteria in the mouth can significantly affect gut health and help predict the risk of chronic liver disease, a study has found.
Each year, more than two million people die from advanced chronic liver disease (ACLD).
In the study, published in the journal Nature Microbiology, 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 microbiomes undergo significant changes as liver disease worsens, with alterations in the oral microbiome detectable even at earlier stages of the disease.
In healthy individuals, bacterial communities differ substantially between body sites.
However, in patients with liver disease, oral and gut microbiomes became increasingly similar as the disease progressed, with nearly identical bacterial strains recovered from both the mouth and gut.
“These strains are typically found in the mouth and are rarely present in the healthy gut. However, we observed increases in the absolute abundance 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 had 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 that these enzymes were active by testing isolated bacteria from stool samples and synthesising 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 up 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
