Tissue and Salivary NMR Metabolomics in Reticular-Type Oral Lichen Planus

Oral lichen planus (OLP) is a chronic T-cell–mediated autoimmune disease, with low potential for malignant transformation. Its etiology remains unclear, necessitating immunohistochemical and molecular-level studies to enhance diagnosis and management. Thirteen patients diagnosed with OLP and 13 healthy controls (HCs) were enrolled from three centers. Mucosal tissue samples collected during diagnostic biopsies and unstimulated whole saliva samples were analysed. A comprehensive approach was taken, with high-resolution magic angle spinning (HR-MAS) 1H-NMR spectroscopy performed on biopsies and liquid 1H-NMR spectroscopy on saliva samples to identify potential biomarkers correlated with OLP. Multivariate analyses effectively distinguish OLP patients from HC based on metabolic profiles, with key metabolites contributing to the separation. In tissue, triglycerides were significantly elevated in OLP biopsies, whereas amino acids such as glutamate, glutamine, taurine, glycine and alanine were significantly decreased in OLP tissues compared with controls (p < 0.05). Salivary analysis revealed significant alterations in compounds of bacterial origin—such as isobutyrate, isocaproate, isovalerate and agmatine—suggesting dysbiosis in OLP patients. The metabolic alterations identified highlight the roles of oxidative stress and lipid metabolism in OLP pathogenesis and suggest potential biomarkers for OLP diagnosis. These findings provide new insights into the molecular mechanisms of OLP, which may have important clinical implications for future diagnostic and therapeutic strategies.