Localization of collagenase in chronically inflamed guinea pig temporal bone

Bone destruction, commonly associated with chronic otitis media, requires collagen degradation. Collagenase, a neutral protease, appears to be an essential component in the process of collagen breakdown. Collagenase was identified within chronically inflamed and normal guinea pig temporal bones using an immunohistochemical technique with fluorescein isothyocyanate and peroxidase-antiperoxidase labels. Localization of the enzyme identifies sites of matrix resorption. Collagenase was found in osteoclasts, osteocytes, mononuclear inflammatory cells, and at resorbing margins. Inflammation increased the intracellular collagenase content of inflammatory bone osteocytes when compared to normal osteocytes using a microspectrofluorometer. It appears that the inflammatory process directly influences bone destruction through the action of mononuclear inflammatory cells and indirectly by stimulating bone cells to increase their proteolytic enzyme production.