Biochemical study of protease inhibitors in experimental otitis media with effusion

Proteolytic degradation of the middle ear mucosa (MEM) by lysosomal proteases is one of the major factors inducing pathologic changes of the MEM. In recent years, the kinetics of the protease-inhibitor systems and their roles in the pathogenesis of human otitis media with effusion (OME) have been investigated. α1-Antitrypsin (α1-AT) and α2-macroglobulin (α2-M), which constitute about 90% of all the inhibitory function in plasma, and low molecular weight (LMW) inhibitors are known to regulate the proteolytic activity in the MEM. In this study, both immunochemical and functional assays of the major protease inhibitors α1-AT and α2-M were performed in middle ear effusions (MEEs) from three experimental OME models (serous otitis media [SOM], purulent otitis media [POM], and SOM + POM), in order to identify these protease inhibitors and to explore their roles in the disease processes of various types of otitis media.