Background. Matrix metalloproteinases (MMPs), gelatinases, have been associated with otitis media with effusion (OME), but the role of collagenase-2/matrix metalloproteinase-8 (MMP-8) in OME has not been studied previously. We studied the levels, isoenzyme distribution, and activation of MMP-8 in childhood OME, and also the levels of pro-and active forms of MMP-2 and-9 as well as 120 kDa gelatinase complexes were assessed. Methods. Seventy middle ear fluid (MEF) samples were collected from 54 children with OME and classified to mucoid (n = 39) or serous (n = 31). MMPs were studied from MEF samples by time-resolved immunofluorometric assay, Western immunoblotting, and gelatin-zymography. Results. MMP-8 was found in its active form in MEF of children with OME. MMP-8 levels were significantly higher in mucous relative to serous OME. The pro-or active MMP-2 and-9 were found in MEF, but no MEF type-specific differences were found. Conclusion. Our results suggest that MMP-8 may play a role in the pathogenesis of childhood OME. New therapeutic strategies with MMP inhibitors targeting MMP-8, but allowing MMP-8 to carry out the protective action, may play a role in the future treatment of otitis media and OME. However, further studies of this topic are needed.
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