IL-6, calcium, salivary amylase activity and cortisol as a salivary biomarker-combination associated with obesity: a pilot study

INTRODUCTION: As obesity continues to escalate to pandemic levels worldwide, innovative approaches for early diagnosis, risk stratification, and disease monitoring are urgently needed. Saliva presents a promising non-invasive method for biomarker-based screening in obesity.

OBJECTIVE: This study aimed to utilize a multi-biomarker approach to explore associations between salivary biomarkers and obesity. This was done by measuring a pre-selected panel of obesity-related salivary biomarkers and comparing their levels between individuals with and without obesity.

METHODS: Unstimulated saliva was collected from 57 individuals, including 27 individuals diagnosed with obesity (BMI ≥ 30 kg/m 2) and 30 non-obese controls (BMI < 30 kg/m 2). Various biochemical techniques were used to quantify salivary total protein content, α-amylase activity (sAA), cortisol, interleukin 6 (IL-6), mucin 5B (MUC5B), albumin and calcium ions (Ca 2+).

RESULTS: The results indicated lower Ca 2+, sAA, and MUC5B levels ( P  < 0.05) and higher IL-6 and cortisol levels ( P  < 0.05) in the obese group compared to non-obese controls. In the obese group, Ca 2+ correlated positively with most biomarkers, with sAA (r = 0.632, P  < 0.05) and IL-6 (r = 0.449, P  < 0.05) showing the strongest associations.

CONCLUSIONS: In conclusion, this study highlights IL-6, Ca 2+, sAA, and cortisol as a potential salivary biomarker-combination associated with obesity warranting further investigation. The observed changes in the salivary biomarker levels of the obese group may reflect underlying metabolic dysregulations, highlighting the advantage of a multi-biomarker approach to better capture early metabolic and inflammatory processes associated with obesity. To further validate these findings, large clinical studies with diverse, well-matched cohorts, as well as longitudinal studies, are needed.