CD103+ tissue resident memory T cells in oral lichen planus

Abstract

Oral lichen planus (OLP) is a chronic inflammatory disease that results from a disorder of infiltrating T cells. Tissue resident memory T cells (TRM cells) are CD103-expressing T cells that persist within previously inflamed oral mucosa in the long term to provide locally rapid defensive responses against encountered pathogens. They are also speculated to be associated with some diseases including OLP. This study aimed to determine the number and the proportion of CD103+ TRM cells in the OLP lesions as compared to the normal mucosa. Immunohistochemical study of CD3+, CD4+, CD8+ and CD103+ cells in 15 OLP tissues and 15 normal mucosa tissues was performed. An unpaired t-test, a paired t-test, a Mann-Whitney U test and a Wilcoxon Signed Ranks test were used to analyze the data. A p-value < 0.05 was considered statistically significant. The results revealed significant increases in the numbers of CD3+, CD4+, CD8+ and CD103+ cells per area (cells/mm2) in the OLP lesions as compared to the normal mucosa (p < 0.001). These cells were frequently expressed in the lamina propria rather than the epithelium (p < 0.005). The proportion of CD103+ cells to CD3+ cells (%) in the lamina propria of the OLP lesions was lower than that of the normal mucosa. (p < 0.001), but this significant difference was not found in the epithelium between both tissues (p = 0.062). Furthermore, the OLP lamina propria showed lower proportion of CD103+ cells to CD3+ cells than the OLP epithelium (p < 0.001). In conclusion, this study demonstrates the several-fold increase in the density of CD103+ cells in the OLP lesions that may suggest the association between CD103+ TRM cells and the pathogenesis of OLP.