The Possible Role of Sclerostin in the Pathogenesis of Tympanosclerosis.

OBJECTIVE: The aim of this study was to investigate sclerostin (SOST) expression in a rat model of experimental tympanosclerosis (TS) and its possible role in the formation of TS. MATERIALS AND METHODS: Thirty-four SD rats were randomly divided into 2 groups: experimental group (n = 17) and normal group (n = 17). The left tympanic cavities in the experimental group were inoculated with methicillin-resistant Staphylococcus aureus. The changes of tympanic membranes were examined and recorded under otoendoscope. Haematoxylin-eosin staining was adopted to detect the morphological changes in the tympanic membrane and middle ear mucosa. Immunohistochemistry and Western blot analysis were used to observe the expression of SOST, Wnt3a, ß-catenin, and P-ERK1/2. RESULTS: In the experimental group, sclerotic lesions were observed in 54.5% ears in the end of 6 weeks. Morphological changes such as mucosa incrassation, inflammatory cells infiltration, fibrous tissue proliferation, and interstitial tissue incrassation prominently appeared in the tympanic membrane and middle ear mucosa. SOST protein was mainly distributed in the cytoplasm of epithelial cells and gland cells, the expression of which increased significantly in the calcified experimental ears. In addition, expression levels of Wnt3a, ß-catenin, and P-ERK1/2 increased significantly in the calcified group too. CONCLUSION: The upregulated expression level of SOST may be involved in the formation of TS, first, through the pro-phosphorylation of ERK1/2 in the inflammatory stage, and then through the enhancement of Wnt3a in the osteogenic stage.

Metagenomics Analysis of Bacterial Population of Tympanosclerotic Plaques and Cholesteatomas.

Objective Chronic otitis media can cause cholesteatomas or tympanosclerosis; however, the pathophysiology of such conditions is not completely known. The aim was to identify a bacterial genome that might be present in tympanosclerotic plaques and cholesteatomas using sequence analysis of the gene responsible for the transcription of 16 ribosomal RNA (rRNA). Study Design Metagenomics analysis of the samples. Setting Samples were collected and evaluated at tertiary care centers. Subjects and Methods Sixty-five tympanosclerotic plaques and 37 cholesteatomas were evaluated. The polymerase chain reaction (PCR) was performed using primers designed for the amplification of the gene responsible for the transcription of bacterial 16 rRNA. The PCR-positive samples were sequenced via Sanger method, and 46 selected samples were analyzed with next-generation sequencing (NGS). Results Sanger sequencing revealed the presence of bacterial genomes in a total of 18 of the 102 samples tested. Sequencing of these genomes indicated the presence of Alloiococcus otitis, Staphylococcus aureus, Achromobacter xylosoxidans, Escherichia coli, Staphylococcus sciuri, Staphylococcus caprae, Parvimonas spp., and Bacillus sp. in the tested samples. The NGS showed 1 or more different bacterial genomes in 44 (95.7%) of the 46 samples tested. Predominately, genome of Clostridiales (27 samples), Staphylococcaceae (24 samples), Peptoniphilaceae (12 samples), and Turicella otitidis (9 samples) were identified. Conclusion The middle ear is inhabited by a diverse microbial community than that previously known. With the use of molecular biology, it has become easier to identify the bacterial genomes and improve our understanding of the role of middle ear microbiota in the pathogenesis of chronic inflammatory ear diseases.

Role of Chlamydia pneumoniae and Helicobacteria pylori in the development of tympanosclerosis.

The etiology of tympanosclerosis (TS) is not known, but TS commonly develops secondary to acute and chronic otitis media (COM). Since calcification process in TS resembles that of atherosclerosis (AS), pathogens that are related to pathogenesis of AS may be involved in development of TS. This prospective and controlled study, performed at a tertiary referral center, investigated a possible relationship between the presence of Chlamydia (C.) pneumoniae and Helicobacter (H.) pylori and the development of a tympanosclerotic plaque. The presence of C. pneumoniae was examined in the surgical specimens of 62 patients (29 females and 33 males; age range 10-70 years, mean age 30.8 ± 13.3 years), including 30 patients with TS, 14 patients with cholesteatoma, and 18 patients with chronic suppurative otitis media (CSOM). The presence of H. pylori was examined in the surgical specimens of 88 patients (41 females and 47 males; age range 6-70 years, mean age 32.5 ± 14.8 years), including 35 patients with TS, 22 patients with cholesteatoma, 20 patients with CSOM, and 11 patients with otosclerosis. Tympanosclerotic plaques and control specimens from the cholesteatoma, polypoid mucosa, or mucosal portion of the perforations and stapes supra structure were examined for the presence of H. pylori and/or C. pneumoniae using real-time polymerase chain reaction analysis. The analysis demonstrated that specimens from the tympanosclerotic plaques and the other types of COM were all negative for C. pneumoniae and H. pylori. An association between C. pneumoniae or H. pylori infection and the development of TS or other types of COM could not be established.

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-ß1 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 ß1 (TGF-ß1) were assessed by western blot and immunohistochemistry staining, and the mRNA level of TGF-ß1 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-ß1 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-ß1.