Does exogenous nitric oxide influence tympanosclerosis? An experimental study

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, β-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, β-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.

The effect of caffeic acid phenethyl ester (CAPE) on tympanosclerosis

OBJECTIVE

To investigate the effects of caffeic acid phenethyl ester (CAPE) on tympanosclerosis.

MATERIALS AND METHODS

Thirty-two male Sprague Dawley rats were separated into 4 groups as CAPE (n = 10), alcohol (n = 10), control (n = 8) and normal (n = 4) groups. All tympanic membranes except normal group were myringotomised and type 3 Streptococcus pneumoniae strains was injected into their middle ears. Myringotomies were repeated for 5 weeks. Intraperitoneal (i.p) CAPE were administrated to the CAPE group at 10 μmol/kg/day and 10% ethyl alcohol administrated to the alcohol group for 5 weeks. The control group were left untreated. Findings of myringosclerosis were recorded by otomicroscope at sixth week. Then, all rats were sacrificed and tympanic membrane thickness and severity of middle ear mucosal inflammation evaluated histopathalogically.

RESULTS

Severity of myringosclerosis was significantly higher in the alcohol and control groups compared to the CAPE group (p < 0.001), but was not significant when alcohol and control groups were compared (p = 0.17). The tympanic membrane thickness measured in the alcohol and control groups were significantly higher compared to the CAPE group (p < 0.001), but was not significant when alcohol and control groups were compared (p = 0.17). The severity of inflammation in the middle ear mucosa was significantly higher in the alcohol and control groups compared to the CAPE group (respectively, p < 0.001, p = 0.03). The severity of inflammation in the middle ear mucosa was not significant between alcohol and control groups (p = 0.30).

CONCLUSION

CAPE has anti-inflammatory and antioxidant effects on the development of MS in myringotomized rats, so reduces the severity of tympanosclerosis.

Genetic polymorphisms affecting antioxidant enzymes are present in tympanosclerosis patients

BACKGROUND

This study investigated genetic polymorphisms affecting the inducible nitric oxide synthase, superoxide dismutase and catalase enzymes in chronic otitis media patients with and without tympanosclerosis, and the role of genetic susceptibility in the disease aetiology.

METHODS

A total of 162 patients who underwent surgery for chronic otitis media were divided into two study groups: a tympanosclerosis group and a chronic otitis media group. A third, the control, group comprised 188 healthy volunteers. Venous blood samples were evaluated using reverse transcriptase polymerase chain reaction.

RESULTS

There was a significant difference in GG genotype distribution of the -277A>G polymorphism in the NOS2 gene between the tympanosclerosis and control groups (p T) polymorphism in the SOD2 gene (p > 0.05). There were significant differences in the TT genotype distribution of the -21A>T polymorphism in the CAT gene between the tympanosclerosis and control groups, and between the chronic otitis media and control groups (p < 0.05).

CONCLUSION

These results suggest that genetic predisposition may play a role in the aetiopathogenesis of tympanosclerosis.

The effect of topical sodium thiosulfate in experimentally induced myringosclerosis

OBJECTIVES/HYPOTHESIS

The purpose of this study was to investigate the effect of topical sodium thiosulfate (STS) in experimentally induced myringosclerosis (MS).

STUDY DESIGN

A prospective experimental animal study.

METHODS

Thirty Wistar albino rats were bilaterally myringotomized. The right ears were treated with STS or saline daily, and the left ears were left untreated and used as controls. The tympanic membranes were observed by otoendoscopy weekly, and tympanometric measurements were performed. All animals were histopathologically examined for myringosclerotic plaques.

RESULTS

Under otoendoscopy, myringosclerosis were observed around the handle of the malleus and near the annular region. The numbers of myringosclerotic ears were significantly more frequent in control and saline groups compared with the STS group (P < .05), and the formation of MS was more severe in control and saline groups compared with STS group (P < .05). Using tympanometric measurement, significantly reduced magnitudes of maximum admittance were observed in control and saline groups compared to normal and STS groups (P < .05). Under histopathologic examination, the tympanic membrane of the STS group appeared thinner than the control group (P < .05), with reduced calcium deposition than control and saline groups.

CONCLUSIONS

Our results show that sodium thiosulfate has a preventive role in the development of myringosclerosis in the experimental animal model.