Math 1, retinoic acid, and TNF-α synergistically promote the differentiation of mucous cells in mouse middle ear epithelial cells in vitro

BACKGROUND: A key issue in otitis media (OM) is mucous cell metaplasia in the middle ear mucosa, a condition for hyperproduction of mucus in the middle ear mucosa and development of chronic OM. However, little is known about the driving force for the differentiation of mucous cells in OM. METHODS: Mouse middle ear epithelial cells (mMEECs) were used in this study to test whether Math1, a critical transcription factor for the development of mucous cells in the intestine, synergizes with inflammatory cytokines (tumor necrosis factor-alpha (TNF-alpha)) and other epithelial differentiation factors (retinoid acid (RA)) to induce the differentiation of mMEECs into mucus-like cells in vitro. Simultaneously, Math1 was transduced into the middle ear mucosa in order to observe whether it induces mucous cell hyperplasia in vivo. RESULTS: Math1 significantly increased the mucus cell numbers in the middle ear mucosa of mice. Math1, in the presence of TNF-alpha and epithelial differentiation factor RA, synergistically promoted the differentiation of mMEECs into mucus-like cells through upregulation of mucins and their chaperones: trefoil factors in vitro. RA treatment for 12 h activated Math1, although RA alone had very limited effects on mucus-like cell differentiation. CONCLUSION: Math1 plays a critical role in the pathogenesis of OM by induction of mucous cell differentiation in the presence of TNF-alpha and RA.