Imbalances in the oral microbiome linked to symptomatic hand osteoarthritis

A study published online in the open-access journal RMD Open has linked specific imbalances and disruptions in the oral microbiome to symptomatic hand arthritis.

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Its findings suggest that the microbial environment of the mouth may influence the disease process of hand arthritis, which is associated with pain, stiffness and reduced grip strength and can severely impair quality of life. The oral microbiome plays a role in systemic inflammation and interacts closely with the gut microbiome, which is significantly associated with symptomatic hand arthritis.

To assess the role of the oral microbiome, saliva samples from 52 people with symptomatic hand arthritis recruited from a community-based osteoarthritis study and 712 people without the condition were analyzed using ribosomal RNA gene sequencing.

Distinct shifts in mouth bacteria

Compared with samples taken from participants without hand arthritis, samples from participants with symptomatic hand arthritis showed significantly lower oral microbial richness and altered composition.

Specifically, the abundance of Trichococcus bacteria was significantly higher in the symptomatic hand arthritis samples and positively associated with the severity of hand arthritis symptoms. Trichococcus abundance in the oral microbiome was also positively associated with the gut microbial tyrosine metabolism pathway—a metabolic pathway previously implicated in hand arthritis.

Samples from participants with symptomatic hand arthritis also displayed reduced oral-gut microbiome correlations compared with controls, suggesting the balance between these two microbial communities was disrupted.

Limits on cause and precision

This is an observational study and, as such, can't establish cause and effect. The authors highlight some limitations, most importantly that the oral microbiome was profiled using 16S rRNA gene sequencing, which provides taxonomic and compositional insights but lacks the resolution to identify specific bacterial species or strains. The cross-sectional design meant a temporal or causal relationship between oral microbiome alterations and symptomatic hand arthritis could not be established.

Symptomatic hand arthritis was diagnosed at the hand level rather than at the individual joint level, which may have introduced some misclassification. The small sample size may limit statistical power and prevent detection of additional species with more modest associations with pathogenesis. Finally, although several known confounders were adjusted for, confounding from unmeasured variables cannot be excluded.

Evidence points to a mouth-gut link

Nevertheless, the authors conclude that oral microbiome dysbiosis and disruption of the oral-gut microbiome network are associated with prevalent symptomatic hand arthritis and suggest a potential role for the oral-gut microbiome axis in SHOA pathogenesis.

"This study provides the first evidence linking oral microbiome alterations to symptomatic hand arthritis and highlights their correlation with gut microbiome dysbiosis, suggesting a potential role for the oral-gut microbiome axis in symptomatic hand arthritis pathogenesis," they say.

Larger studies are needed to confirm these associations, and longitudinal cohort studies are required to determine whether these microbial changes precede the development of symptomatic hand arthritis or are consequences of the disease.

More information: Oral microbiome dysbiosis and oral-gut microbial network disruption in hand osteoarthritis: data from the Xiangya Osteoarthritis Study, RMD Open (2026). DOI: 10.1136/rmdopen-2026-006962

Provided by British Medical Journal