Metagenomic insights into oral microbiota dynamics in diabetic and non-diabetic periodontal disease: a pilot study

Subgingival microbial dysbiosis is one of the key reasons behind periodontitis, a chronic inflammatory disease, which is further get severe in the presence of type 2 diabetes mellitus (T2D). Although changes in taxonomic composition have been well established, the functional interactions and metagenomic profiles across different stages of the disease remain unclear.

A shotgun metagenomic analysis was performed on subgingival dental plaque samples from 16 individuals, divided into healthy, staged periodontitis, and diabetic periodontitis groups. Group-wise DNA pooling was done for maximum DNA yield. Further, Alpha/beta diversity, taxonomic profiling, pathogen-probiotic ratios, and metabolic pathway abundance were analyzed and studied.

The healthy group showed the highest alpha diversity, especially in the core biosynthetic pathways. On the other hand, the earlier stages of periodontitis showed a unique community structure and the lowest alpha diversity. Early periodontitis also showed the highest abundance of commensals like Actinomyces and Bifidobacterium, along with increased UMP/guanosine and L-arginine biosynthesis pathways. The advanced periodontitis group had an increase of red complex bacteria and loss of probiotics. An increase of the degradative pathways, such as L-histidine degradation, had also been observed in this stage. The diabetic periodontitis group had a distinct microbial profile that included Capnocytophaga and a considerable metabolic shift toward lipid metabolism and glycolysis, with higher overall microbial diversity than the other periodontitis groups.

The results clearly show that the subgingival microbial and functional patterns are different across the stages of the disease and metabolic status, which can be developed for underscoring the importance of targeting early metabolic shifts to prevent dysbiosis.