A new experimental model of acquired cholesteatoma

Association Between Earwax-Determinant Genotypes and Acquired Middle Ear Cholesteatoma in a Japanese Population

OBJECTIVE

A single-nucleotide polymorphism 538G>A in the human ABCC11 gene is a determinant of the earwax morphotype. ABCC11 538GG and GA correspond to wet earwax and 538AA to dry earwax. Despite a putative positive correlation between the frequency of the 538G allele and the prevalence of cholesteatoma, minimal clinical information is currently available. We aimed to evaluate this association between the ABCC11 genotypes and acquired middle ear cholesteatoma.

STUDY DESIGN

Case-control study.

SETTING

Single-center academic hospital.

METHODS

We recruited 67 Japanese patients with acquired middle ear cholesteatoma (cholesteatoma group) and 100 Japanese controls with no history of middle ear cholesteatoma. We assessed the ABCC11 genotypes for all participants. Clinical information was collected from the cholesteatoma group. The genotype data of 104 Japanese people from the 1000 Genomes Project who represent the general population were used.

RESULTS

The proportion of participants with ABCC11 538GG or GA was significantly higher in the cholesteatoma group than in the control group or general Japanese population (P < .001). The ABCC11 538G allele frequency was also significantly higher in the cholesteatoma group than in the control group or general Japanese population (P < .001). Multivariate logistic regression analyses revealed a significant association between the ABCC11 genotype and acquired middle ear cholesteatoma (odds ratio, 5.49; 95% CI, 2.61-11.5; P < .001).

CONCLUSION

Our results suggest that the ABCC11 genotypes could be associated with the development of acquired middle ear cholesteatoma among Japanese people.

Experimental models of cholesteatoma: A review

Cholesteatoma describes the keratinized, stratified squamous epithelium in the middle ear and mastoid, which has osteoclastic activity and is capable of bone resorption. Its origin is unknown and remains a topic of current investigation. In addition, ongoing studies are investigating new molecules for treatment. This review summarizes the various experimental models of cholesteatoma.

Mastoid cholesteatoma: a result of metaplasia

Presence of cholesteatoma in the middle ear of the patients with chronic mucosal otitis media has been reported in the literature. But presence of cholesteatoma only in the mastoid, in the absence of cholesteatoma in the middle ear of a patient with chronic mucosal otitis media, is not reported in the literature. In this article three cases of mastoid cholesteatoma, in patients with a clinical picture of chronic mucosal otitis media is reported along with the literature review.

Autologous meatal skin graft implantation and intratympanic injection of Pseudomonas aeruginosa: a new experimental mouse model of acquired middle ear cholesteatoma

AIM

To create an experimental model for the biomedical research of middle ear cholesteatoma.

METHODS

Cholesteatoma was induced in the right ears of mice. An autologous meatal skin graft was implanted into the middle ear via the tympanic membrane followed by an intratympanic injection of Pseudomonas aeruginosa. Six weeks after surgery, the formation of acquired cholesteatoma was evaluated by macroscopic examination, CT scan, and histological analysis. The expressions of TNF-α, IL-1β, and IL-6 were measured with real-time PCR. Auditory-evoked brain stem response was used for assessing the changes in hearing levels.

RESULTS

None of the mice died during the modeling time. By the sixth postoperative week, cholesteatoma had successfully formed in 23 out of 25 mice, which equals a success rate of 92%. A CT scan revealed that the cholesteatoma was eroding the cochlea. Furthermore, histological analysis demonstrated a cystic structure covered by stratified squamous epithelium and keratin desquamation in the lamellae inside the cystic cavity in the bullae. All mice with experimentally induced cholesteatoma showed hearing impairment and an upregulated expression of TNF-α, IL-1β, and IL-6.

CONCLUSION

The present study successfully developed a mouse model of acquired middle ear cholesteatoma, which provides an extremely valuable tool for auditory and biomedical research. The modeling approach is technically easy and has a high success rate.

Development of animal models of otitis media

Otitis media is defined as inflammation of the middle ear, including the auditory ossicles and the Eustachian tube. Otitis media is a major health problem in many societies. The causes of otitis media includes infection and anatomic/physiologic, host, and environmental factors. In general, otitis media is a childhood disease, and anatomic and physiologic changes have great effects on its development. Thus, in vitro or human experimental studies of otitis media are difficult. Several experimental animal models have been introduced to investigate the pathogenesis and treatment of otitis media. However, none are ideal. The aim of this review is to provide a brief overview of the current status of animal models of otitis media with effusion, acute otitis media, and cholesteatoma. This review will assist determination of the most appropriate animal models of otitis media.

Development of animal models of otitis media

Otitis media is defined as inflammation of the middle ear, including the auditory ossicles and the Eustachian tube. Otitis media is a major health problem in many societies. The causes of otitis media includes infection and anatomic/physiologic, host, and environmental factors. In general, otitis media is a childhood disease, and anatomic and physiologic changes have great effects on its development. Thus, in vitro or human experimental studies of otitis media are difficult. Several experimental animal models have been introduced to investigate the pathogenesis and treatment of otitis media. However, none are ideal. The aim of this review is to provide a brief overview of the current status of animal models of otitis media with effusion, acute otitis media, and cholesteatoma. This review will assist determination of the most appropriate animal models of otitis media.

Effect of intratympanic mitomycin C on the development of cholesteatoma and otitis media in rats

Objective:

To determine whether the administration of mitomycin C prevents propylene glycol exposure from inducing middle-ear cholesteatoma and otitis media, in a rat model.

Methods:

Twenty-four Wistar rats underwent intratympanic injections on days 1, 8 and 15, via the tympanic membrane pars tensa, in both the right and left ears. The right ear injection solution contained 50 per cent propylene glycol, gentamicin and saline (0.9 per cent), while the left ear solution contained 50 per cent propylene glycol, gentamicin and mitomycin C. Animals were sacrificed and examined.

Results:

There were statistically significant differences between the control and experimental groups for tympanic bulla mucosal thickness (p = 0.004) but not for tympanic membrane thickness (p = 0.371), otomicroscopic findings (p = 0.262), or the presence of exudate (p = 0.125), fibrosis (p = 1.000) or cholesteatoma (p = 0.687).

Conclusion:

Intratympanic mitomycin C was ineffective in preventing middle-ear cholesteatoma and otitis media in this rat model.

Identification of Id1 in acquired middle ear cholesteatoma

OBJECTIVES

To determine (1) the relationship between chronic inflammatory changes in the ossicular chain area (OCA) and the formation of cholesteatoma and (2) the correlates between aberrant gene expression and abnormal proliferation of cholesteatoma.

METHODS

Two hundred sixty-four ears with chronic otitis media that had undergone ear surgery were included in this study for statistical analysis of the relationship between abnormalities in the OCA and cholesteatoma. Fourteen middle ear cholesteatoma specimens were collected for immunohistochemical analysis of candidate molecules involved in the abnormal proliferation of keratinocytes. A cell model was used for verification of candidate molecule involvement.

RESULTS

The formation of cholesteatoma was accompanied by chronic inflammatory changes in the OCA, including granulated tissue, adhesion, and stagnating effusion. The inhibitor of the DNA-binding (Id1) gene, which is involved in controlling cell cycle progression, was abundantly expressed in cholesteatoma epithelium. In vitro studies indicate that Id1 regulated the expression of nuclear factor kappaB, cyclin D1, proliferating cell nuclear antigen, and cell cycle progression of keratinocytes,

CONCLUSIONS

Chronic inflammation in the OCA is closely related to the formation of cholesteatoma. The Id1/nuclear factor kappaB/cyclin D1/proliferating cell nuclear antigen signaling pathway is involved in the abnormal proliferation of keratinocytes in acquired cholesteatoma.

The pathophysiology of cholesteatoma

The pathogenesis of middle ear cholesteatoma continues to be highly debated. In recent years, there has been a substantial improvement in the understanding of the pathophysiology of this disease. This chapter provides a summary of the history and evolution of cholesteatoma and a review of the recent literature that pertains to the pathophysiology of congenital and acquired cholesteatoma. An emphasis is placed on the mechanism of osteolysis and the factors predictive of aggressiveness and recidivism.