Effect of endotoxin on the advancing front between cultured middle ear mucosa and epidermis. A preliminary study.

The formation of Cholesteatoma is often accompanied by infection, and is very likely to be influenced by inflammatory mediators. Endotoxin, a strong inflammatory mediator, may play an important role in cholesteatoma pathogenesis. It has been demonstrated in middle ear effusions, and it causes marked reactions in middle ear epithelium and epidermis, both in vivo and in vitro. The effect of endotoxin on a simulation of the advancing front of cholesteatoma was investigated in this study. We developed a co-culture model composed of a simultaneous culture of rat middle ear mucosa and rat meatal epidermis in one culture dish, to which endotoxin was added. During the culture period the addition of endotoxin to the co-culture delayed take-over of the meatal epidermis by the middle ear mucosa, in comparison with control cultures. Morphological changes included the clustering of microvilli in co-cultures exposed to endotoxin. Although these results are preliminary, they suggest that endotoxin disturbs the normal healing process of the middle ear cavity.