Objectives: To determine expression levels of proliferation markers in the labial salivary gland (LSG) of xerostomic patients.
Methods: Nineteen xerostomic and five non-xerostomic patients were referred from various specialties for LSG biopsy. All biopsies were H&E stained and immunohistochemical analysis was performed using the TUNEL method for apoptosis and Ki-67 and PCNA for proliferative assays. Apoptotic and proliferative indexes were calculated.
Results: Sections of LSG epithelial cells showed similar modest levels of apoptosis and Ki-67 positive staining from xerostomic patients and normal control subjects. However, the proportion of PCNA positive cells in xerostomic patient samples was significantly higher than that of the non-xerostomic group.
Conclusions: Based on Ki67 and TUNEL staining, proliferation and apoptosis are not elevated in xerostomic patients, including confirmed Sjögren's syndrome patients. Since PCNA plays a key role in repairing oxidative DNA damage induced by reactive oxygen species (ROS), elevated PCNA levels indicate that an increase in ROS-induced oxidative DNA damage could occur in the xerostomic LSG. The activation of DNA repair mechanism in the salivary epithelial cells may cause the reduction in gland function. Therefore, PCNA over-expression may provide an objective criterion for xerostomia.
This study is supported by the Fort Gordon Dental Activity with support from MCG School of Dentistry.