From Healthy Oral Mucosa to Epithelial Dysplastic Lesions: A Metabolic Profiling Study on Saliva

Objectives The present multicentric case-control study aims to explore and compare salivary metabolites in healthy oral mucosa and dysplastic epithelial lesions. We search for metabolic salivary patterns characteristic of oral lichen planus (OLP), dysplastic and non-dysplastic oral leukoplakia (OL) in comparison to the salivary metabolic profile of healthy controls (HC). Methods Unstimulated whole saliva from 54 subjects was collected before surgical procedures (e.g., third molar extraction, clinically benign oral lesions excision). Demographic, anamnestic, and clinical data, risk factors were recorded for each patient. We evaluated their general oral health (Decay Missing Filled Teeth index-DMFT and Full Mouth Plaque Score-FMPS), periodontal health status (Periodontal Screening and Recording,PSR), presence or absence of infectious diseases and other potential pathological conditions. Biopsies histopathological evaluation was performed, and results were classified in 13 patients with OLP, 13 with non-dysplastic OL, 13 with dysplastic OL and 15 HC. Salivary samples analysed by proton Nuclear Magnetic Resonance Spectroscopy (1H-NMR). Multivariate statistics was performed using the Metaboanalyst 5.0 platform. Results We have profiled the saliva samples of all the study participants, identifying 68 metabolites by comparation between OLP patients and HC and 72 compounds by comparation between OL patients and HC. The analysis highlighted: 1. for OLP, an altered composition in bacterial-derived metabolites, namely creatinine, isobutyrate, uracil, alanine (most concentrated in HC) and formate (most concentrated in OLP) (VIP score > 2), suggesting a dysbiotic state associated with the disease; 2. for OL, 3 differential metabolic profiles reflecting a trend in salivary composition from healthy controls to the dysplastic form of the pathology. The most discriminant compounds, exhibiting a VIP score > 2, are urocanate (most concentrated in OL with dysplasia), isobutyrate, and creatinine (most concentrated in HC). Conclusions The exploration of the salivary metabolome of patients with OLP and OL through 1H-NMR generated a panel of metabolites able to distinguish dysplastic lesions from healthy oral mucosa.