Induction of mucin gene expression in middle ear of rats by tumor necrosisfactor-alpha: Potential cause for mucoid otitis media

Mucoid otitis media (MOM) is characterized by viscous fluid, high in mucin concentration, which accumulates in the middle ear cavity. Recent studies s uggest that initial infection in the middle ear cleft may be key to the dev elopment of MOM. However, factors of the initial infection attributed to th e stimulation of mucin production are not clearly understood, This study de monstrated that tumor necrosis factor (TNF)-alpha, a proinflammatory cytoki ne in mucoid effusion, markedly increased Muc2 mucin mRNA expression in mid dle ear epithelium, in a time- and dose-dependent manner. Parallel to this was a marked increase in mucin glycoprotein in middle ear fluid. Also, TNF- alpha demonstrated an autocrine and/or paracrine effect on the expression o f endogenous TNF-alpha gene in the middle ear, which may contribute to the production of mucin in this study. These findings suggest that TNF-alpha pl ays an important role in the development of MOM by stimulating mucin metabo lism.