Gene expression levels of salivary inflammatory markers and their association with obesity, glycemic status, and beta cell function

Abstract

Introduction

Chronic low-grade inflammation is central to the pathogenesis of obesity-related metabolic disorders, and identifying circulating inflammatory biomarkers may facilitate early risk stratification and targeted preventive strategies. This study investigated whether salivary mRNA expression levels of the pro-inflammatory cytokines interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) differ between obese and non-obese individuals and examined their associations with glycemic status and β-cell function.

Methods

Salivary mRNA levels of IL-6 and TNF-α were quantified using real-time polymerase chain reaction. Bivariate analyses explored fold-change differences across glycemic categories, obesity status, and C-peptide levels, and adjusted logistic regression models were employed to assess independent associations with metabolic outcomes, controlling for age, sex, smoking, periodontal disease, and co-variables.

Results

Multinomial logistic regression showed that IL-6 mRNA fold-change was independently associated with obesity (aOR = 1.49, 95% CI: 1.09–2.08) and overweight (aOR = 1.56, 95% CI: 1.11–2.16), while TNF-α was independently associated with overweight (aOR = 1.74, 95% CI: 1.03–2.92); however, no significant associations were found between cytokine expression and glycemic status or C-peptide to glucose ratio.

Conclusion

Salivary mRNA expression levels of IL-6 and TNF-α may serve as non-invasive biomarkers for obesity-associated inflammation, supporting their potential utility in metabolic risk stratification, although their role in early glycemic dysregulation warrants further investigation.