Microbial dysbiosis in oral cavity determines obesity status in adolescents.

The prevalence of obesity is rapidly increasing among adolescents in Kuwait. The ecological and dynamic changes within the oral microbiota during this developmental stage remain elusive. This study aimed to investigate the impact of body mass index (BMI) on salivary microbiome diversity and composition in Kuwaiti adolescents by utilizing next-generation sequencing technologies. DNA was extracted from saliva samples of 62 Kuwaiti adolescents enrolled in the nationwide Kuwait Healthy Lifestyle Study, categorized as underweight, normal weight, overweight, and obese based on their BMI percentiles. The 16 S metagenomic profiling was performed to identify the key oral lineages and genera associated with obesity through comprehensive analysis involving taxonomic composition, co-occurrence networks, and key metabolic profiles. Our study reveals an inverse relationship between oral bacterial diversity and obesity status in Kuwaiti adolescents. The obese and overweight groups showed comparatively low microbial taxa compared to those of normal weight. We identified three potential microbial biomarkers linked to obesity and overweight: Prevotella melaninogenica, Veillonella dispar, and Veillonella parvula. The abundance of Neisseria subflava and Rothia mucilaginosa in normal weight adolescents indicates their role in weight homeostasis. In- silico analysis of differentially expressed microbiota revealed increased activity of major metabolic enzymes such as glucose- 6- phosphate dehydrogenase, pyruvate oxidase, and glycogen phosphorylase, along with oxidative stress- related enzymes including superoxide reductase and glutathione peroxidase in obese and over-weight adolescents. Conversely, normal weight adolescents exhibited heightened activity of pyruvate synthase and tRNA- methyltransferase, which are linked to antioxidative pathways and balanced energy metabolism. Our study highlights taxonomic and functional shifts in the oral microbiota of Kuwaiti adolescents across varying BMI categories, signifying key microbial markers that could pave the way for future research focused on microbiome- targeted interventions in obesity management.