Serum matrix metalloproteinases and tympanosclerosis

Does systemic clarithromycin therapy have an inhibitory effect on tympanosclerosis? An experimental animal study

Objective:

To demonstrate the inhibitory effects of clarithromycin on in vitro tympanosclerosis.

Method:

Twenty-eight rats were divided into three groups: a clarithromycin group, a non-clarithromycin group and a negative control group. Those in the first two groups were injected with Streptococcus pneumoniae following a myringotomy, and tympanosclerosis was experimentally induced. Oral clarithromycin therapy was administered in the clarithromycin group. The other groups received no medical treatment.

Results:

All eardrums in the clarithromycin and non-clarithromycin groups developed myringosclerosis, but there was only one eardrum, in the clarithromycin group, with very severe myringosclerosis. In the clarithromycin group, 11 ears showed no inflammation and there were no ears with severe inflammation. In the non-clarithromycin group, there were 11 ears with severe inflammation. The mean eardrum thickness in the clarithromycin group was 20.93 µm and in the non-clarithromycin group it was 42.71 µm.

Conclusion:

Acute otitis media and myringotomies induced tympanosclerosis, but clarithromycin reduced the severity of tympanosclerosis.

Combining use of captopril and losartan attenuates the progress of Streptococcus pneumoniae-induced tympanosclerosis through the suppression of TGF-β1 expression

Objectives

In this study, using an Streptococcus pneumoniae-induced tympanosclerosis (TS) model, we explored the effects of captopril and losartan in the treatment of TS and the possible mechanisms.

Study Design

A prospective experimental animal study.

Methods

We set up the TS models in both guinea pig and wistar rat by inoculation of type-3 Streptococcus pneumoniae microorganisms and then treated the animals with the combining use of captopril and losartan. Otomicroscopy was employed to observe the development of TS. Auditory brainstem response was used to test the hearing function of animals. Hematoxylin-eosin and von Kossa staining were performed to determine the morphological changes and calcium depositions. The protein expressions of transforming growth factor β1 (TGF-β1) were assessed by western blot and immunohistochemistry staining, and the mRNA level of TGF-β1 was measured by quantitative reverse transcription- polymerase chain reaction.

Results

The combining use of captopril and losartan attenuated TS responses in terms of a decrease in the TS incidence and the ABR threshold, a reduction of hyalinization and calcification in the middle ear mucosa and the thickness of the mucosa. In addition, the TGF-β1 expression was decreased at both protein and mRNA levels.

Conclusion

Our data indicate, for the first time, that the combining use of captopril and losartan obviously attenuates TS progress through inhibiting the overexpressing of TGF-β1.