# Decreased Serum and Salivary Levels of Aquaporin 5 in Oral Lichen Planus

## TL;DR

This study finds lower levels of Aquaporin 5 in the blood and saliva of oral lichen planus patients, linking it to dry mouth and impaired salivary function.

## Contribution

The study is the first to investigate Aquaporin 5 levels in oral lichen planus patients with xerostomia.

## Key findings

- Aquaporin 5 levels in serum and saliva were significantly lower in OLP patients.
- Salivary flow was reduced in OLP patients, correlating with higher xerostomia.
- Aquaporin 5 may be involved in mucosal repair and cancer risk in OLP.

## Abstract

Oral lichen planus (OLP) is an autoimmune disease with unknown etiology. Many OLP patients complain of xerostomia, and studies are still ongoing to find the reason for this manifestation. Aquaporin 5 has been expressed in salivary glands, and its physiological significance in transferring water as transcellular is properly identified. In this study, for the first time, we have investigated the serum and salivary levels of aquaporin 5 (as a salivary gland biomarker) in oral lichen planus patients with xerostomia.

Thirty patients with OLP and xerostomia and 30 healthy individuals were chosen. The flow of stimulatory and non‐stimulatory saliva was calculated, and the serums, in addition to salivary levels of aquaporin 5, were determined.

The level of Aquaporin 5 in serum and its output in stimulatory, and non‐stimulatory saliva were significantly decreased, the stimulatory and non‐stimulatory saliva flow was reduced, and the degree of xerostomia was significantly higher in the OLP group.

Aquaporin 5 is implicated in OLP patients in several ways such as impaired salivary functioning, xerostomia or dry mouth, diminished repair ability of the mucosal lesion, increased apoptosis, and probable carcinogenesis in this premalignant lesion.