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Bone resorption factors in chronic otitis media
Abstract:
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.
Insights
Collagenase in rat chronic otitis media suggests fibroblasts, stimulated by prostaglandin E2 from macrophages, contribute to bone resorption. This highlights fibroblast-epithelial cell interaction in the disease process.
Area of Science:
- Biochemistry
- Cell Biology
- Pathology
Background:
- Chronic otitis media involves bone resorption.
- The role of collagenase and cellular interactions in this process is not fully understood.
Purpose of the Study:
- To identify collagenase in rat chronic otitis media.
- To investigate the role of macrophages, prostaglandin E2, and cell-cell interactions in collagenase production and bone resorption.
Main Methods:
- Immunohistochemical staining (peroxidase-antiperoxidase) to detect collagenase.
- Culture of rat peritoneal macrophages with lipopolysaccharide (endotoxin).
- Measurement of prostaglandin E2 levels and confirmation by immunofluorescent staining.
Main Results:
- Collagenase was localized in fibroblasts, mononuclear cells, and osteoclasts in bone-resorbing areas.
- Collagenase was found in fibroblasts adjacent to epithelial basal cells.
- Endotoxin-activated macrophages produced minimal collagenase but significantly increased prostaglandin E2.
- Prostaglandin E2 may stimulate fibroblast collagenase production.
Conclusions:
- Activated macrophages, via prostaglandin E2, may stimulate fibroblast collagenase production.
- Fibroblast-epithelial cell interactions appear to enhance bone resorption in chronic otitis media.