Abstract:

Objective To investigate the compositional characteristics and potential functional alterations of the oral microbiome in patients with periodontitis comorbid with depression. Methods A total of 32 patients with periodontitis and comorbid depression were selected as the depression-associated periodontal disease group, while 33 patients without depression but with periodontal disease were selected as the non-depression periodontal disease group. Unstimulated saliva samples were collected from participants and subjected to 16S rRNA sequencing on the Illumina NovaSeq 6000 platform. Alpha and beta diversity and differences in microbial abundance were analyzed. Indicator species analysis (ISA), linear discriminant analysis effect size (LEfSe) for differential taxa screening, and BugBase functional prediction were used to identify depression-associated characteristic genera and their phenotypic features. Results A total of 1 617 399 high-quality sequences and 3 451 non-redundant amplicon sequence variants (ASVs) were obtained from 32 samples in the depression-associated periodontal disease group. In the non-depression periodontal disease group, 33 samples obtained 1 568 119 high-quality sequences and 3 729 ASVs. The total number of ASVs in the two groups was 1 587. The alpha diversity indices of saliva microbiota in the depression-combined-with-periodontitis group, namely Shannon, Simpson, Chao1 and Faith's PD, were higher than those in the non-depression-periodontitis group (P<0.05). The beta diversity analysis revealed that there were significant differences in the community structure of oral bacteria between the two groups (P<0.05). ISA analysis identified three characteristic genera of the non-depressed periodontitis group: Atopobium, Prevotella_7 and Megamonas. LEfSe analysis indicated that genera enriched in the periodontitis-with-depression group included Neisseria, Haemophilus, Lautropia, Capnocytophaga and Actinobacillus. The genera enriched in the non-depressed periodontitis group mainly included Atopobium, Megamonas, Prevotella_7, Veillonella, Prevotella, Actinomyces, Gemella, and the Eubacterium nodatum group. BugBase predictions indicated that compared with the non-depression periodontitis group, the depression with periodontitis group had higher relative abundances in phenotypes such as aerobic bacteria, bacteria containing mobile genetic elements, biofilm formation, Gram-positive bacteria, potential pathogenicity and stress tolerance (P<0.05), while its relative abundance was lower in anaerobic bacteria and Gram-negative bacteria（P<0.05). Conclusion Depressive state may be related to the imbalance of oral microbiome in the occurrence and development of periodontitis patients with depression through a “psychological-microbial-inflammatory” pathway.

Key words: depressive disorder, periodontitis, mouth, microbiota, 16S rRNA sequencing