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TOPLINE:

A systematic review found that patients with autoimmune liver diseases had altered oral microbiota — notably increased Veillonella — which in some studies was associated with elevated salivary inflammatory markers; some studies also reported gut dysbiosis and signs of leaky gut.

METHODOLOGY:

• Prior research has linked an imbalance in oral microbiota to gut and liver inflammation and immune changes. Shifts in intestinal microbiota have been linked to chronic liver conditions including fatty liver disease and autoimmune disorders.
• Researchers conducted a systematic review to determine whether patients with autoimmune liver diseases had altered oral microbiota and whether these alterations were associated with inflammatory signals.
• They searched three databases through January 2026 and included English-language observational studies that compared oral (and sometimes gut) microbiota between patients with autoimmune liver diseases and healthy individuals.
• Data from oral (mostly saliva), stool, and occasional biopsy samples were extracted, focusing on DNA-based microbiota analyses, salivary inflammatory marker levels, and gut barrier measures when available.
• Researchers assessed study quality and risk for bias using the Newcastle-Ottawa Scale.

TAKEAWAY:

• The review included six studies involving 252 patients with autoimmune hepatitis, a small subgroup with primary biliary cholangitis, and 345 healthy individuals. Study quality scores ranged from 4 to 7, with most having a moderate risk for bias.
• All studies reported altered oral microbiota in patients with autoimmune liver diseases. Most studies reported an increased abundance of Veillonella, some reported reduced abundances of Streptococcus and Fusobacterium, and one small study reported a higher abundance of Eubacterium in those with primary biliary cholangitis.
• Several studies reported higher levels of salivary inflammatory markers in patients than in healthy individuals. The abundance of Veillonella correlated positively with these markers, whereas that of Streptococcus showed an inverse relationship.
• Studies with gut samples or biopsies found reduced gut microbial diversity, taxonomic shifts, increased intestinal permeability, and bacterial translocation. A few small studies have built microbiome-based diagnostic models reporting high accuracy.

IN PRACTICE:

“These findings are interpreted as mechanistic support for the oral-gut-liver axis, suggesting a biological pathway through which oral dysbiosis may contribute to hepatic inflammation,” the authors of the study wrote. “The evidence available so far suggests that the dysbiosis in oral microbiota may constitute a significant factor in immune-inflammatory processes of autoimmune liver diseases.”

SOURCE:

The study was led by Fariba Esperouz, University of Foggia, Foggia, Italy. It was published online in Clinics and Research in Hepatology and Gastroenterology.

LIMITATIONS:

The authors acknowledged the need for future studies to better establish whether the observed microbial changes caused autoimmune liver diseases and related mechanisms.

DISCLOSURES:

The research received funding from the Health Extended Alliance for Innovative Therapies, Advanced Lab-research, and Integrated Approaches of Precision Medicine. The authors declared having no competing interests.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.