This study aims to explore whether Connexin 43 (Cx43) in salivary extracellular vesicles (EVs) can serve as a biomarker for diagnosing oral lichen planus (OLP), an inflammatory oral mucosal disorder.

The study assessed disease activity in OLP patients using the reticulum-erosion-ulcer disease activity score. Saliva EVs were isolated and purified with an EV Enrichment Kit. Transmission electron microscopy was used to examine the morphology and size of EVs, while Western blotting verified EV biomarkers. ELISA measured serum inflammatory factors, such as TNF-α and IL-17. The importance of Cx43 in the diagnosis of OLP was evaluated using receiver operating characteristic (ROC) curve analysis, and correlations were determined through Pearson analysis.

The average diameter of isolated saliva EVs was approximately 110 nm, and they expressed high levels of known EV biomarkers. In OLP patients, both Cx43 mRNA and protein levels were significantly higher compared to healthy controls. Furthermore, Cx43 mRNA and protein levels increased gradually with increased disease severity, from the reticular type to the more severe erosion type of OLP. Cx43 mRNA and protein levels were found to effectively diagnosing OLP and correlated significantly with disease activity scores. Moreover, elevated Cx43 mRNA and protein levels showed strong positive correlations with serum TNF-α and IL-17 levels in OLP patients.

Cx43 mRNA and protein levels in salivary EVs serve as effective biomarkers for diagnosing OLP and are significantly associated with disease activity and inflammatory markers. This makes Cx43 a promising candidate for non-invasive diagnosis of OLP.