Analysis of Oral Microbiome in Bariatric Surgery Patients and in Mice

Objectives: Obesity and bariatric surgery induce systemic alterations that can be reflected at the oral cavity. The nature of these alterations is still not conclusive. This research aims to investigate the effect of obesity and bariatric surgery on the oral health status and oral microbiome in humans and in mice.
Methods: The oral status of obese patients (pre-surgery, 1/2Y post-surgery) and lean volunteers was examined, and categorized accordingly to- gingivitis, caries, and periodontitis. Patients’ oral plaque microbiome was explored using next-generation sequencing of 16S rDNA and assessed by analysis and statistical tests.
Furthermore, 40 C57BL/6 mice were fed high-fat diet, and go through: experimental periodontitis (PERIO±), sleeve gastrectomy (SG±). Wight and glucose levels were monitored and oral and gut microbiome were collected. Maxillary jaws were harvested for alveolar bone volume estimation using μCT and for H&E and TRAP staining.
Results: Microbial diversity was significantly higher in bariatric patients, and was increased post-surgery. Microbiome composition showed distinguished clustering trend between the three groups. Higher prevalence of Streptococcus and pseudomonas in control group, while Neisseria, Veillonella, Aggregatibacter-segnis and copnocytophaga were higher in obese patients. Interestingly, oral Bacteroidota/Proteobacteria ratio was the highest in the bariatric group indicating higher dysbiosis.
In mice, systemic indicators and maxillary volume were significantly different between SG+/ PERIO+ to SG-/PERIO- groups. Oral microbiome diversity increased in SG+/PERIO+ group post-surgery compared to baseline and pre-surgery. The oral microbiome composition was significantly different between SG-/PERIO+, SG+/PERIO+. Sanguibacter oral abundance increased with obesity, while Alkanindiges-illinoisensis decreased. Streptococcus-equi and Paraburkholderia-bryophila decreased post-surgery. Higher Lachnospiraceae abundance in SG-/PERIO+ compared to SG-/PERIO-. Interestingly, oral gavage of P.g induced gut microbiome changes.
Conclusions: All together, these results suggest that there is an association between oral health and obesity and that oral microbiome is affected by obesity, and weight loss after bariatric surgery.