Mouse middle ear epithelial cells were incubated with 20 ng/mL of TNFα and 10−9 M of RA for two weeks on 8-well chamber slides (media and factors were supplied every two days). Immunohistochemistry showed that these factors increased the expression of goblet cell markers, MUC2 and TFF3, suggesting that this could be a model of mucous cell metaplasia in infectious otitis media. Math1 was located only in the cytoplasm in the control culture, however, the administration of TNFα + RA made Math1 translocate into nuclei. This Math1 activation (translocation to nuclei) probably triggers the expression of MUC2 and TFF3.
