Serum Catestatin Level as a Novel Biomarker of Oral Lichen Planus

Background/Objectives: Oral lichen planus (OLP) is a chronic immune-mediated disease of the oral mucosa in which T-cell infiltration, epithelial injury, and stress-related neuroendocrine signaling appear to intersect. Catestatin (CST), a peptide generated from chromogranin A (CgA), modulates catecholamine release and inflammatory cell responses; however, its association with localized mucosal inflammation in OLP has not been clarified. This study aimed to compare serum CST levels between OLP patients and healthy controls and to examine their association with clinical subtype, disease severity, and vitamin D status. Methods: In this cross-sectional study, 51 patients with clinically and histopathologically confirmed OLP and 60 healthy controls were enrolled at the University Hospital of Split. Serum CST was quantified using ELISA. OLP severity was assessed with the REU score by a single experienced oral medicine examiner who was blinded to laboratory results, and pain and burning were recorded separately using 0–10 VASs. Results: Serum CST levels were significantly higher in OLP patients compared to healthy controls (p < 0.001). CST levels showed a strong positive correlation with the REU total score (r = 0.781, p < 0.001), as well as with VAS pain (r = 0.708, p < 0.001) and VAS burning (r = 0.729, p < 0.001). Erosive OLP exhibited significantly higher CST levels compared to the non-erosive subtype (p < 0.001). Furthermore, serum vitamin D levels were significantly lower in OLP patients (p < 0.001), with no significant correlation observed between CST and vitamin D levels. Conclusions: Serum CST levels were higher in OLP patients and showed close associations with REU scores and symptoms, with the strongest signal observed in erosive disease. CST may therefore contribute to the neuroendocrine-immune profile of OLP and may be useful as an adjunctive marker of clinically active or erosive disease. Larger prospective studies including salivary and tissue-based CST measurements are needed before CST can be used for routine monitoring.