Sjögren's syndrome is an autoimmune disease characterized by xerostomia and keratoconjunctivitis sicca. The relationship between xero-stomia and proliferative activity in human gingival epithelium is not known. Proliferating cell nuclear antigen (PCNA) is a nuclear protein associated with the cell cycle. Nuclear PCNA immunoreactivity is found in the proliferative compartment of normal tissues. The aims of this study were to evaluate PCNA expression in oral gingival epithelium of healthy and inflamed gingiva obtained from patients with Sjögren's syndrome, and to compare the results to age- and gender-matched subjects with normal salivary function.
Eighteen Sjögren's syndrome patients and 28 controls (14 with chronic periodontitis and 14 with no clinical evidence of periodontal disease) were included in the study. Biopsies were obtained from both inflamed and healthy gingiva. The expression of PCNA was evaluated in formalin-fixed, paraffin-embedded gingival samples using an immunoperoxidase technique and PC10 monoclonal antibody to PCNA.
PCNA expression was observed both in the basal and suprabasal layers, and was found to be more prominent in the suprabasal layers. Proliferative index (PI) in inflamed gingiva was significantly lower in the Sjögren's syndrome group. However, no significant difference was observed between the study and control groups with respect to PI in healthy gingiva. In both groups, PI was found to be increased due to inflammation.
Our data indicate that proliferative activity is observed in the suprabasal layers and, less frequently, in the basal layer. Inflammation caused increased proliferative activity. However, this positive effect of inflammation on epithelial cell proliferation decreased significantly with a lack of saliva. Therefore, it appears that saliva-derived biological mediators may also contribute to increased proliferative activity observed during inflammation.