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

Juliana M. C. Brant,Luciana V. Rodrigues,Maria Cássia F. Aguiar,Helenice A. M. Grandinetti,Anilton C. Vasconcelos

doi:10.1590/s0103-64402012000500016

Abstract

The oral lichen planus (OLP) is a chronic inflammatory disease, probably autoimmune, with different clinical forms. The most common types are the reticular and the erosive ones. Apoptosis participates in the destruction of basal keratinocytes, but its role in the perpetuation of the subepithelial lymphocytic infiltrates was not yet investigated. To evaluate the involvement of apoptosis in the epithelium and in subepithelial lymphocytic infiltrates, 15 samples of reticular and erosive OLP and 10 samples of healthy oral mucosa were collected and processed histologically. Apoptosis was quantified in the epithelium and in inflammatory cell infiltrates. TUNEL reaction was used to measure apoptosis in the infiltrates. Erosive OLP showed more intense epithelial apoptosis than reticular OLP and controls. In contrast, apoptosis in the inflammatory cell infiltrates was more frequent in reticular than in erosive OLP. Lymphocytes were the predominant cells within the inflammatory cell infiltrates and were more frequent in erosive OLP than in reticular type. These results suggest that different apoptotic levels are involved in the erosive/reticular switch in OLP, determining different clinical presentations. In conclusion, decreased apoptosis in inflammatory infiltrates may contribute to the persistence of T lymphocytes, worsening the attack to the epithelium in erosive OLP.

Highlights

Oral lichen planus (OLP) is a presumably autoimmune prevalent chronic disease that affects the tongue and oral mucosa with papule lesions or rashes [1]
That morphology was suggestive of cells undergoing apoptosis, which was confirmed by TUNEL reaction (Fig. 3B)
The Apoptotic Indexes (AI) of inflammatory infiltrates in the reticular type was higher (18.88 ± 0.81) than in erosive OLP (6.58 ± 0.39), with p

Summary

Introduction

Oral lichen planus (OLP) is a presumably autoimmune prevalent chronic disease that affects the tongue and oral mucosa with papule lesions or rashes [1]. The pathogenesis of OLP remains unclear [2,3], but apoptosis has been reported in epidermal cells, indicating a role in epithelial destruction [4]. Erosive/ ulcerative OLP constitute the most destructive form and causes a great oral discomfort [5,7]. The clinical differences between reticular and erosive forms appear to be a reflection of the biological variations found in these two types of OLP [6]. The cause of the OLP remains speculative, many findings are suggestive of a persistent immune disorder mediated by T lymphocytes [8]. Apoptosis is a mechanism in the destruction of the basal cell layer [9], its role in the subepithelial inflammatory cell infiltrates has not yet been investigated. There is increasing evidence that deregulated apoptosis is a mechanism of immune evasion and that delayed apoptosis, resulting in prolonged inflammatory cell survival, is important in persistence of the inflammation in tissues [10]

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