Investigating the Salivary Microbiome Through Meta-Genomics: A Clinical Study on Periodontal Health

Background and Aim: Periodontal diseases are highly prevalent oral health conditions with significant diagnostic challenges. Very few studies have addressed the microbial assessment of the salivary microbiome as biomarker development platform. The objective of this study was to investigate the differential abundance of the oral microbial taxa in the saliva samples of periodontal disease patients and healthy controls for oral microbiota-based diagnostic biomarker discovery. Materials and Methods: The saliva samples were collected from a well-phenotyped cohort under the National Institute of Dental and Craniofacial Research Institutional Review Board-approved protocol. Genomic DNA was extracted from the samples. Microbiota profiles were generated by processing variable regions of 16S rRNA gene using next-generation sequencing by Illumina MiSeq platform. Differential abundance testing was performed using DESeq2. One of the clustering methods of the rank-ration test was presented in the heat map, along with the relative taxon abundance. Finally, the metagenomics profiling was performed. Results: Porphyromonas gingivalis and Tannerella forsythia were significantly more abundant in the saliva samples of periodontal disease patients in terms of differential abundance. Streptococcus sanguinis has potential as negative disease-associated oral microbiota-based diagnostic biomarker. The findings were statistically significant and validated by the findings of previous oral microbiome studies. Conclusion: Our findings provide evidence that the salivary microbiome could be rich source of diagnostic biomarkers missing in the current diagnostic strategies for the periodontal diseases such as gingivitis and periodontitis. These biomarkers might not only shed light on the disease pathogenesis, but also lead us to identify new molecular targets for the improved treatment and management of the periodontal diseases.