Role of apoptosis in erosive and reticular oral lichen planus exhibiting variable epithelial thickness

Abstract

Oral lichen planus (OLP) is a chronic inflammatory disease with different clinical types. Reticular and erosive forms are the most common. Although the cause of OLP remains speculative, many findings suggest auto-immune involvement, mediated by T lymphocytes against the basal keratinocytes. Inflammation, mechanical trauma or toxic agents can affect the epithelial homeostasia. Increased apoptosis may cause a decrease in epithelial thickness reflecting in the activity of the lesion. The objective of this study was to evaluate the occurrence of apoptosis and epithelial thickness in reticular and erosive forms of OLP. 15 samples of OLP each type (reticular and erosive) plus 10 of healthy mucosa were collected and processed. After morphometry, the apoptotic index and epitelial thickness were obtained. TUNEL and M30 CytoDEATH immunohistochemical assay were used to validate the morphologic criteria used. Apoptosis in the erosive OLP was significantly more intense than in the reticular type and both forms of OLP presented more apoptosis than the healthy oral mucosa. Healthy oral mucosa was thicker than both OLP forms and thicker in OLP reticular form than in the erosive one. The clinical differences between reticular and erosive forms of OLP are related to variations in epithelial thickness and in intensity of apoptosis.

A comparative study of apoptosis in reticular and erosive oral lichen planus

“…The pathogenesis of OLP remains unclear (2,3), but apoptosis has been reported in epidermal cells, indicating a role in epithelial destruction (4). Reticular pattern is the most frequent clinical presentation and appears in the form of a network of connections and overlapping white lines (5) combined with a few symptoms and reflecting a milder stage of the disease (6,7).…”

Serum Level of Interleukin-17 in Patients with Erosive and Non-erosive Oral Lichen Planus

“…17 Areas with atrophy were also seen more frequently in the histopathological views of erosive oral lichen planus. Based on the results of the latter study indicating a higher inflammation and cell destruction in erosive OLP, it could be interpreted that as IL-17 increases in inflammatory diseases, it results in secretion of high amounts of pre-inflammatory cytokines, and subsequently it is effective in formation of OLP and even its different presentations.…”

Eradication of damaged keratinocytes in cutaneous lichen planus forms demonstrated by evaluation of epidermal and follicular expression of CK15, indices of apoptosis and regulatory protein S100

“…The apoptotic index (AI) was used as a comparative figure (AI = TNAEC/TNEC ×100), as described previously [54]. AI was estimated for the basal, spinous, and overlying epidermal layers, as well as follicular localization separately.…”