Análise clínico-patológica e qualitativa da expressão de mediadores inflamatórios teciduais no líquen plano oral

Abstract

Oral lichen planus (OLP) is a chronic immunoinflammatory mucocutaneous condition of unknown etiology and pathogenesis. Studies focusing on the presence of cytokines in OLP, especially interleukin (IL)-6, IL-17 and IL-18, are scarce, as well as the correlation of clinical and histological characteristics with the presence of inflammatory mediators. All lesions diagnosed as OLP and oral lichenoid lesions (OLL) were reviewed from the files of the Oral Pathology laboratory, Dental School, Rio de Janeiro State University, and their clinicopathological characteristics were analyzed. Forty cases diagnosed as OLP were selected for additional immunohistochemical reactions directed against IL-6, IL-17 e IL-18. The total sample was composed by 221 cases and showed that OLP presented a predilection for adult females, mostly affected by lesions with the reticular pattern and located in the buccal mucosa. The 40 cases selected for the immunohistochemical reactions included patients with a mean age of 53 years, with no gender predilection, and with lesions located mostly in the buccal mucosa (85%), gingiva/alveolar mucosa (47%) and tongue (42%). The clinical pattern showed reticular lesions in 14 patients (35%) and reticular and atrophic/erosive lesions in 26 patients (65%). Symptoms were reported by 53% of the patients and included mostly burning sensation and local discomfort. Histological analysis showed that the epithelial thickness was normal, atrophic, or hyperplastic in, respectively, 17 (43%), 9 (22%) and 14 (35%) cases. The presence of hyperkeratosis was observed in 21 cases (53%), and exocytosis of T CD4+ and T CD8+ lymphocytes was present in, respectively, 17 (42%) and 30 (75%) cases. Immunohistochemical analysis showed that, in general, IL-6 was the most expressed IL both in epithelium and connective tissue. IL-17 expression was considered intense in the connective tissue from 40% of the cases. IL-18 expression was considered mostly mild/moderate both in epithelium (40% of the cases) and connective tissue (45% of the cases). The presence of exocytosis was associated with a higher expression of the ILs and expression of IL-17 was higher in epithelium showing hyperkeratosis. The results from the present study showed that the clinical characteristics of OLP and OLL are distinct and can be useful in differentiating these two diagnostic entities. The histological and immunohistochemical features suggest that the studied ILs are more expressed when there is exocytosis of both T CD4+ and T CD8+ lymphocytes. Expression of the ILs can be associated with the epithelial alterations encountered in OLP, participating in the pathogenesis and modulating the expression of the disease.