RESUMO
OBJECTIVES: Oral lichen planus (OLP) is a chronic, inflammatory condition, classified by the World Health Organization as a premalignant lesion. We performed this study to evaluate the correlation between microRNA-137 (miR-137) and CD8 oral tissue expression in OLP patients. MATERIALS AND METHODS: Twenty OLP patients [classified into three groups: (a) papular, reticular, or plaque; (b) atrophic; and (c) erosive] and 20 healthy controls were subjected to biopsy of the oral mucosa. To evaluate CD8 tissue expression, we performed immunohistochemical examination, followed by immunostaining and computerized quantification. The expression of miR-137 was evaluated using real-time quantitative PCR. We used SPSS software (version 15 for windows) to perform the statistical analysis. RESULTS: Our analysis showed an increased tissue expression of CD8 (p < 0.01) and reduced expression of miR-137 (p < 0.001) in OLP patients, compared to the control group. Moreover, there was a statistically significant difference (p = 0.001) between OLP subgroups in terms of CD8 tissue expression [highest in erosive OLP and lowest in papular/reticular/plaque OLP]. However, these subgroups showed no significant difference (p = 0.168) in terms of miR-137 expression. A negative correlation (p < 0.05) between tissue expression of miR-137 and CD8 was noted with a varying correlation coefficient in different OLP subgroups (-0.250 in erosive OLP, -0.491 in atrophic OLP and -0.616 in papular/reticular/plaque OLP). CONCLUSIONS: Our findings indicate reduced expression of miR-137 and a reverse correlation between tissue expression of miR-137 and CD8 in the oral mucosa of OLP patients. CLINICAL RELEVANCE: Future studies should investigate the therapeutic potential of miR-137 overexpression in OLP patients.