The expression of filaggrin in oral submucosal fibrosis

To study the expression and distribution of filaggrin (FLG) in oral submucous fibrosis (OSF) and to explore the significance of FLG in the occurrence and development of OSF.

Ten cases with a normal oral mucosa (normal buccal mucosa group) and 30 cases of tissues with OSF lesions, including 10 cases each in the early (early OSF group), moderate (middle OSF group) and advanced stages (late OSF group), were selected. FLG was analyzed by immunohistochemistry. The FLG-positive cells were counted to calculate the percentages of cells with FLG-positive expression in each group.

FLG expression was negative in most of the normal buccal mucosa group specimens and was positive in the OSF buccal mucosal epithelial specimens. With aggravation of the OSF lesion, the number of FLG-positive cells increased. In the early OSF group, FLG-positive expression was mainly concentrated in the granular and keratinized epithelial layers. In the middle OSF group, the number of FLG-positive epithelial cells increased gradually. In the late OSF group, almost all epithelial cells were FLG-positive in the cytoplasmic nucleus. The percentages of FLG-positive cells in the early, middle and late OSF groups were (24.63 ± 9.06)%, (54.23 ± 10.63)% and (83.97± 8.72)%, respectively. The percentage of FLG-positive cells was significantly higher in the OSF group than in the normal mucosa group (P < 0.05).

FLG was expressed at a higher level in the OSF epithelium than in the normal oral mucosal epithelium and was upregulated in the OSF epithelium with aggravation of the OSF lesions. Abnormal FLG expression may be related to the terminal differentiation disorder of OSF epithelial keratinocytes.