Experimental models of cholesteatoma: A review

The Effect of Oral Montelukast Administration in Cholesteatoma Development and Inflammation: An Experimental Animal Model

HYPOTHESIS

We hypothesized that oral montelukast treatment could inhibit cholesteatoma formation in an experimental animal model.

BACKGROUND

Inflammation and excessive proliferation have been described in the histopathology of cholesteatoma. The aim of this study was to determine the effect of oral montelukast on cholesteatoma development.

METHODS

Eighteen healthy female Wistar albino rats weighing 250 g were chosen for the study. The animals were divided into two groups: group 1 received montelukast and group 2 was the control group. Intratympanic propylene glycol injection was administered into the left ears and physiologic serum was instilled into the right ears of the animals on the first, eighth, and fifteenth days. The effects of montelukast administration were evaluated by histological examination of the tympanic membrane and middle ear.

RESULTS

Group 1 (montelukast group) showed significant differences in terms of cholesteatoma formation, granulation, epithelial invagination, and inflammation. Cholesteatoma formation in the left ear was observed in 2 (22%) and 8 (89%) rats in groups 1 and 2, respectively (p = 0.015).

CONCLUSION

Development of cholesteatoma and inflammation was significantly lower in the montelukast-administered group. Thus, oral montelukast was found effective in preventing cholesteatoma formation.

The expression of VEGF and VEGFR in endotoxin induced otitis media with effusion in rats

OBJECTIVE

To investigate the expression and correlation of vascular endothelial growth factor (VEGF) and its receptor with hypoxia-inducible factor-1 α (HIF-1 α) in otitis media with effusion (OME).

METHODS

A rat model of OME was induced by injection of lipopolysaccharide (LPS) into the middle ear. Hematoxylin and eosin (HE) staining was used to observe the pathomorphological changes of the tympanic cavity in the middle ear of rats. Immunohistochemistry (IHC), western blotting and RT-qPCR were used to determine the mRNA and protein expression of VEGF, VEGFR-1, VEGFR-2 and HIF-1α in mucosa of tympanic cavity mucosa, respectively.

RESULTS

In the OME group, the epithelial space of the middle ear mucosa was significantly thickened and infiltration of a large number of inflammatory cells was found on postoperative day (POD), and the otitis media basically subsided 2 weeks after operation. VEGF mRNA expression was significantly increased on POD 1, and its protein expression peaked on POD 3. HIF-1α mRNA expression was significantly increased and peaked on POD 1, while its protein expression began to increase on POD 3 and was significantly expressed in the middle ear mucosal epithelium. HIF-1α mRNA showed a positive correlation with VEGF mRNA and VEGFR-1 mRNA expression.

CONCLUSION

VEGF mainly plays a role in the acute phase of OME, and it is abundantly expressed mediated by HIF-1α. And then it play a role in vasodilatation and increase of vascular permeability, thus promoting the generation of middle ear effusion.

Single dose intratympanic mesna application inhibits propylene glycol induced cholesteatoma formation

Objective:

Mesna (i.e. sodium 2-mercaptoethanesulfonate; C2H5NaO3S2) has been used in otological surgery such as cholesteatoma dissection and tympanic membrane lateralisation in atelectatic ears. However, this study aimed to investigate its effect on cholesteatoma formation.

Methods:

A total of 20 Wistar rats were divided into two groups of 10 animals. The right and left ears of control animals were treated with saline (saline control group; n = 10 ears) and propylene glycol plus saline (propylene glycol control group; n = 10 ears), respectively. In the mesna group, both ears were treated with propylene glycol plus mesna (n = 20 ears). On days 1, 8 and 15, the saline control group had intratympanic injections of 0.2 ml saline and the propylene glycol control and mesna groups had intratympanic injections of 0.2 ml 100 per cent propylene glycol. On day 22, the propylene glycol control group had a single intratympanic injection of 0.2 ml saline and the mesna group had a single intratympanic injection of 10 per cent mesna. Animals were killed 12 weeks after the last injection and the temporal bones were sent for histopathological evaluation.

Results:

The cholesteatoma formation rate was 88 per cent in the propylene glycol control group, but was significantly lower in the mesna group (p = 0.01). There were no significant differences in granulation tissue formation (p = 0.498), cyst formation in the bulla (p = 0.381), fibrosis (p = 0.072) and epithelial hyperplasia (p = 0.081) among experimental groups.

Conclusion:

Intratympanic propylene glycol administration is an effective method of promoting experimental cholesteatoma formation. Administration of a single dose of intratympanic mesna inhibited cholesteatoma formation in an animal model.