Cutaneous Lupus Erythematosus: proteomics salivary profiling

Background: Cutaneous lupus erythematosus (CLE) is a complex autoimmune condition with limited data on its molecular underpinnings. Saliva, as plasma filtrate fluid may be a promising tool for biomarkers discovery, since it is an easily accessible biofluid. This study aimed to characterize the salivary proteomic profile of CLE patients compared to healthy controls, to identify potential disease-specific biomarkers. Methods: Ten females diagnosed with CLE and twelve controls without autoimmune conditions were included in the study. Saliva samples were collected under controlled conditions and analyzed using mass spectrometry and chromatography. Proteomic analysis was performed with the nanoElute nanoflow system coupled to a timsTof-Pro mass spectrometer. Results: Among the 104 proteins identified, six showed statistically significant differences between groups. PEBP1 (RKIP), ARG1, TALDO, and CTSZ were upregulated in CLE, while TFF3 and PRDX4 were absent. These proteins are involved in immune regulation, metabolic processes, redox balance, and inflammation. RKIP and ARG1 showed high discriminatory power (AUROC = 1.0), suggesting their potential as CLE biomarkers. Conclusion: This study establishes a distinct salivary proteomic signature in CLE, highlighting a panel of proteins with diagnostic potential. The use of saliva and proteomic techniques offers a powerful approach to unravel CLE pathophysiology and supports future research on non-invasive biomarkers for disease monitoring and personalized care.