Oral and fecal microbiota in oral lichen planus and xerostomia patients: A preliminary study

Background/purpose: The human microbiota constitutes a dynamic community of microorganisms inhabiting the body, with the gut and oral microbiotas being the most prominent. Previous studies have shown associations between oral microbiota disruption and various oral and systemic diseases, along with the involvement of the oral–gut microbiome axis. However, further investigation into the relationship between common oral conditions and microbiota changes remains needed. This study hypothesized that the distinct immune environments in oral lichen planus (OLP) and xerostomia patients result in recognizable microbiota compositions, with additional evaluation of fecal microbiota to explore the oral–gut axis. Materials and methods: Gingival and fecal samples from 8 OLP patients, 19 xerostomia patients, and 10 healthy controls were collected and analyzed using 16S rRNA sequencing with bioinformatic analysis at the phylum level. Statistical comparisons between groups were performed using Student's T-test. Results: Compared with healthy controls, OLP patients showed significant increases in Campylobacterota and Fusobacteria, and decreases in Actinobacteria and Proteobacteria. Xerostomia patients demonstrated a significant increase in Firmicutes. In fecal samples, both OLP and xerostomia patients exhibited significantly reduced Bacteroidetes compared with controls. Conclusion: OLP and xerostomia are associated with distinct oral microbiota patterns, which may aid in early and non-invasive diagnosis. Fecal samples of both patient groups differed significantly from controls in Bacteroidetes, supporting the oral–gut microbiome axis and providing further evidence that oral conditions can influence systemic microbial communities. A major limitation of this study is the relatively small sample size.