Subgingival microbial community structure in HCC patients with periodontitis: 16S rRNA sequencing, functional prediction, and phenotypic profiling.

[BACKGROUND] Periodontal disease (PD) may contribute to the development of hepatocellular carcinoma (HCC) through multiple mechanisms; however, the subgingival microbiota characteristics in patients with HCC and PD have not been systematically characterized.

[MATERIALS AND METHODS] A total of 36 participants were enrolled: 18 in the HCC patients with PD group (HCC-PD) and 18 in the PD group. Subgingival plaque samples were collected, and 16S rRNA high-throughput sequencing was used to analyze the microbial community structure. Functional prediction and phenotypic analysis were employed to compare differences between the two groups.

[RESULTS] A total of 1,178 OTUs were identified in both groups, with 613 unique OTUs in the HCC-PD group and 743 unique OTUs in the PD group. Alpha diversity indices, including the Shannon index (p = 0.0323) and Simpson index (p = 0.0215), showed significant differences between the two groups. Beta diversity analysis revealed significant separation of community structures (PERMANOVA, p = 0.001). At the phylum and genus levels, the relative abundance distributions of dominant microbial communities differed between the two groups. LDA analysis based on LEfSe revealed significantly different characteristic groups at multiple taxonomic levels (from phylum to species) between the two groups. A cladogram further illustrated the distribution of these differentially abundant taxa across taxonomic levels (from phylum to species) using a hierarchical branching structure. Functional prediction revealed that the HCC-PD group was enriched in energy metabolism pathways, while the PD group was enriched in pathways related to environmental adaptation. Phenotypic differences were observed in Gram attribute and oxygen requirement.

[CONCLUSION] The subgingival microbiota of HCC-PD patients differs significantly from that of PD patients in terms of diversity, structure, relative abundance of dominant bacteria, and function, providing microbiological evidence for the 'oral-liver axis' mechanism and offering reference value for disease risk assessment and intervention.