Activities of matrix metalloproteinases and tissue inhibitor of metalloproteinase-2 in idiopathic hemotympanum and otitis media with effusion.

CONCLUSION The expression profile of matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinase-2 (TIMP-2) was specific to the type of middle ear effusion. Further studies are necessary for elucidating its correlation with the sequelae of otitis media with effusion (OME) and idiopathic hemotympanum. OBJECTIVES We aimed to investigate the relative activities of gelatinases (MMP-2 and -9), stromelysin-1 (MMP-3), and matrilysin-1 (MMP-7), as well as measuring TIMP-2 levels in the serous and mucous effusions of OME and hemorrhagic effusion of the idiopathic hemotympanum. MATERIALS AND METHODS Middle ear effusions were collected from patients with OME and idiopathic hemotympanum, and were classified as mucoid, serous, or hemorrhagic. MMP activity in the effusion samples was examined by gelatin and casein zymography. Levels of TIMP-2 were measured by ELISA. Human temporal bone sections, with and without otitis media (OM), were examined histologically. RESULTS One case showed tympanic membrane thinning in the OM group, but none in the control group. While MMP-2 was present in all effusions, the active form of MMP-2 was found only in mucous effusions. MMP-3 and MMP-7 activity was detected only in the mucous effusions. MMP-9 exhibited activity in all effusions, with the highest levels in mucous effusions. TIMP-2 levels were markedly elevated in serous effusions.