MUC5B Alters Oral Mucosa of Oral Lichen Planus Patients with Xerostomia

Abstract

Oral Lichen planus（OLP）is a chronic autoimmune cell-mediated inflammatory disease. Most OLP patients complain of xerostomia/dry mouth due to changes in the oral mucosal protective barrier. Mucin 5B（MUC5B）is the predominate gel-forming mucin in the oral cavity that protects the underlying tissue from mechanical damage, chemical insult, and pathogenic microbes. This study aims to assess MUC5B in OLP subjects and correlate its role in etiopathogenesis. The study included 20 OLP subjects and 10 healthy controls. OLP subjects were divided further into 10 keratotic（reticular）and 10 non-keratotic（atrophic/erythematous）groups based on the clinical criteria. Dryness of mouth was confirmed by the subjective（Xerostomia Inventory, XI; Bother Index, BI）and clinical testing（Clinical Oral Dryness Score, CODS）method. Stimulated, unstimulated saliva and blood samples were collected from subjects. Samples were centrifuged and analysed for MUC5B level using an ELISA kit. The subjective and clinical testing methods which clinically define xerostomia are correlated with the age and sex of the OLP subjects. The stimulated and unstimulated salivary flow rate of OLP subjects was lower（p<0.05）than controls and was associated with the XI, BI, and CODS（p<0.01）. In contrast, the MUC5B level was increased in the serum of OLP subjects compared to controls（p<0.05）. OLP subjects with xerostomia, displayed lower salivary flow, decrease MUC5B in saliva and increase MUC5B in serum. Alteration of MUC5B in the saliva causes oral mucosal alterations affecting the protection of the oral cavity and increase xerostomia in OLP.