Enhancing effect of TNF-α on keratinization of stratified oral mucosal epithelium cultured at an air–liquid interface G. Yamaya, S. Hatakeyama
J Jpn Oral Muco Membr 2009: 15: 59–69 Hyper-orthokeratosis and hyper-parakeratosis are commonly seen in oral mucosal lesions. However, their induced mechanisms are not clarified. Thus, the aim of this study was to evaluate the induction mechanism of hyperkeratinization. A keratinized oral mucosal epithelium (GE1) system was established by culturing oral mucosal cells at an air–liquid interface. Then, they analysed the influence of inflammatory cytokines (TNF-α and IL-6), FGF10 and caspase family inhibitor on the keratinized layer in this system. In the results, TNF-α was found able to significantly thicken the cornified layers ( P < 0.05). Simultaneously TUNEL-positive cells were significantly increased with TNF-α (ANOVA, P < 0.05) and also BrdU-incorporating cells (ANOVA, P < 0.05) were increased. The cornified layer was completely disappeared when keratinized mucosal epithelial cells were cultured with caspase family inhibitor. From these findings, the authors concluded that TNF-α enhanced apoptosis and resulted in hyperkeratinization of the oral mucosal epithelium in air–liquid culture.