Oral Microbial Dysbiosis in Obese Children is Associated with Hypertension

Objectives: The development of obesity is a serious problem throughout the world. In this study, we investigated the changes in oral-microbial composition over a two-year period occurring in 85 Kuwaiti children half of which were selected because they either maintained a healthy-condition or became overweight, and the other-half, developing profound obesity. In addition, we investigated the microbial association with vascular-endothelial-growth-factor (VEGF), and clinical variables related to metabolic syndrome.
Methods: We identified oral-microbiome using 16s-rRNA NGS, amongst healthy (n=27), overweight (n=11), and obese (n=47) adolescents (mean age: 10.85+1.22). In addition, we measured systolic (SBP) and diastolic blood-pressure (DBP), and collected whole-saliva for measurement of 20 protein-hormones by multiplex-assay. Using regression-analysis, we predicted the outcome, systolic-blood-pressure (SBP) and hypertension (HT) (defined as having either high-SBP, or high-DBP, or both), with respect to changes in oral-bacteria-phyla, BMI, and salivary VEGF.
Results: With the onset of obesity, we observed a linear increase in SBP, coupled with significant decrease in Actinobacteria, and an increase in Bacteroidetes phyla. The Actinobacteria-to-Bacteroidetes-ratio (A:B) analyzed by univariate analysis significantly predicted the binary outcome, high-SBP (OR:0.82, 95%CI:0.724-0.934; p=0.003); These results indicate that an increase in Actinobacteria, together with a decrease in Bacteroidetes is 18% less-likely to have high-SBP. In a multivariate-analysis, when we adjusted for obesity (confounding), although marginally significant, we still observed that A:B-ratio demonstrated a protective-effect with high-SBP (AOR:0.89, 95%CI:0.80-1.00). In addition, A:B-ratio strongly predicted the outcome-HT (AOR:0.85, 95%CI:0.76-0.95;p=0.003), adjusted for obesity (AOR:1.47, 95%CI:1.38-1.56;p<0.001), and VEGF– a marker for endothelial-dysfunction (AOR:0.99, 95%CI:0.9993-0.9998;p<0.001).
Conclusions: In summary, we observed that a reduced presence of Actinobacteria and increased presence of Bacteroidetes is associated with a 15% greater likelihood of having HT, adjusted for obesity. The data indicate that the reduction in oral-nitrate-reducing-bacteria (Actinobacteria) contributes to the high blood-pressure, associated with obesity.