Bone resorption factors in chronic otitis media.

Collagenase was identified within naturally occurring rat chronic otitis media by the use of an immunohistochemical technique with peroxidase-antiperoxidase to stain the paraffin. Collagenase was found in fibroblasts, mononuclear cells, and osteoclast cells in the bone-resorbing area. Collagenase was found only in fibroblasts in contact with epithelial basal cells. Macrophages from rat peritoneum were cultured with different concentrations of a lipopolysaccharide. The prostaglandin E2 level reached a maximum during the 12- to 24-hour period in the presence of endotoxin. This prostaglandin E2 was confirmed by immunofluorescent staining. The endotoxin-activated macrophage produced an insignificant amount of collagenase. These findings suggest that activated macrophages may be able to stimulate fibroblast collagenase production through the chemical mediator prostaglandin E2. Also, the interaction between fibroblasts and epidermal cells appears to encourage and enhance the biochemical events resulting in bone resorption in chronic otitis media.