The role of matrix metalloproteinase expression levels in the pathogenesis of tympanosclerosis.

Purpose: Tympanosclerosis is a disease characterized by the accumulation of hyaline calcareous deposits in the tympanic membrane, tympanic cavity, ossicular chain, ligaments, and rarely, in the mastoid. Matrix metalloproteinases, which are involved in physiological and pathologic processes, are also likely to play a role in tympanosclerosis. In our study, we aimed to investigate the presence of MMP 2 and 9 in patients with chronic otitis media with tympanosclerosis and its possible effect on tympanosclerosis severity and prognosis.

Methods: In our study, 45 patients with myringosclerosis or myringosclerosis and intratympanic sclerosis who underwent endoscopic transcanal tympanoplasty due to COM (chronic otitis media) were included in the study group, and 35 patients with only COM, without tympanosclerosis, were included in the control group. Immunohistochemical staining of the mucosa samples of the eardrum and middle ear were compared with MMP-2 and MMP-9 in the study and control groups.

Results: The rate of MMP-2 staining (64.3%) was higher than the control group (42.9%), and the rate of MMP-9 staining (16.7%) was lower than the control group (51.4%) (p < 0.05). The rate of MMP-9 staining in the middle ear mucosa samples (31.0%) was statistically lower than the control group (57.1%) (p < 0.05).

Conclusion: In our study, high levels of MMP-2 staining in the study group and low levels of MMP-9 staining in the control group help to elucidate the complex relationship between both metalloproteinases. Compared with the inadequacy of animal models of tympanosclerosis to mimic the chronic process, our study reveals the late results of MMP-2 and MMP-9 in patients with tympanosclerosis.