Saliva Proteomics Highlights Potential BMI-Related Biomarkers for Forensic and Medical Research

Obesity and underweight pose significant threats to human health as non-communicable diseases. In addition, body shape (like obesity or emaciation) is an important investigative clue in forensic practice. Body mass index (BMI) is a common indicator to reflect body shape of an individual. However, there is a lack of rapid, simple, and effective methods for identifying different BMI individuals. This research aimed to delve into the correlations between salivary proteins and BMI. A total of 418 differential expression proteins (DEPs) were identified through four-dimensional data independent acquisition quantitative proteomics analysis. The Kyoto Encyclopedia of Genes and Genomes analysis revealed that DEPs were primarily involved in oxidative phosphorylation, protein processing in the endoplasmic reticulum, and cholesterol metabolism pathways. Finally, we identified 17 protein markers that were correlated with BMI. Two machine-learning models (random forest and support vector machine) were also built based on these 17 markers. Obtained results demonstrated the efficacy of these 17 protein markers in accurately distinguishing different BMI individuals. In conclusion, our study not only provides potential salivary protein markers for identifying obesity and underweight individuals, it could also present a novel method for inferring BMI of saliva-related samples in forensic case investigation.