Elastin in oral connective tissue modulates the keratinization of overlying epithelium.

AIM: One of the most discernable differences between keratinized and non-keratinized oral mucosas is the quantity of elastin they contain in the connective tissues. Whether elastin modulates the keratin expression of oral epithelial cells is unknown. METHODS: Four specimens containing both keratinized and non-keratinized mucosas were processed for immunohistochemical (IHC) stainings for elastin and four keratins. Six keratinized and non-keratinized portions of oral mucosas were dissected and cultured on an organ culture system. Purified elastin and elastase were added separately to the media. After 14 days, the mucosas were examined for four keratin expressions. Cell cultures of keratinized and non-keratinized gingival fibroblasts were established and tested for elastin expression. Oral mucosa equivalents were then engineered and tested for keratin expression. RESULTS: Keratinized epithelium exclusively expressed keratin-1 and -10 (K1/10), while non-keratinized epithelium expressed keratin-4 and -13 (K4/13). Only non-keratinized fibroblasts expressed elastin in cell culture. Both the native and the engineered keratinized gingiva changed phenotypes and expressed K4/13 when treated with exogenous elastin. On the contrary, the native non-keratinized mucosa started to express K1/10 when elastase eradicated inherent elastin. CONCLUSIONS: Our study demonstrated that the elastin in the oral connective tissue is important for the non-keratinized phenotypes of overlaying epithelium.

Aberrant keratinization of reticular oral lichen planus is related to elastolysis.

OBJECTIVE: Aberrant keratinization is common in oral lichen planus (OLP) on buccal mucosa. Because elastin is crucial for maintaining the nonkeratinized phenotype of oral mucosa, we examined whether inflammatory elastases and the accompanying elastolysis were related to this feature. STUDY DESIGN: Protein and mRNA levels of keratinization-associated keratins (K1/10), nonkeratinization-associated keratins (K4/13), elastin, neutrophil elastase, and macrophage metalloelastase (MMP-12) were compared between normal alveolar mucosa and reticular OLP from buccal mucosa. Normal alveolar mucosae were cultured ex vivo on an organ culture system with and without elastase treatment. After 14 days, the mucosae were examined for 4 keratin expressions. RESULTS: The expressions of K1/10 and elastases increased, whereas those of K4/13 and elastin decreased in OLP. The nonkeratinized mucosa in the organ culture began to express K1/10 when elastase degraded the inherent elastin. CONCLUSIONS: Our study demonstrated that elastolysis in reticular OLP may be related to its aberrant keratinization.