Animal model for cholesteatoma induced in the gerbil: will the profiles of differentiation/growth-regulatory markers be similar to the clinical situation?

HMGB1 Carried by Small Extracellular Vesicles Potentially Plays a Role in Promoting Acquired Middle Ear Cholesteatoma

Cholesteatoma is a specific medical condition involving the abnormal, non-cancerous growth of skin-like tissue in the middle ear, potentially leading to a collection of debris and even infections. The receptor for advanced glycation (RAGE) and its ligand, high-mobility box 1 (HMGB1), are both known to be overexpressed in cholesteatoma and play a potential role in the pathogenesis of the disease. In this study, we investigated the role of small extracellular vesicles (sEVs) in carrying HMGB1 and inducing disease-promoting effects in cholesteatoma. No significant differences in the concentration of isolated sEVs in the plasma of cholesteatoma patients (n = 17) and controls (n = 22) were found (p > 0.05); however, cholesteatoma-derived sEVs carried significantly higher levels of HMGB1 (p < 0.05). In comparison to sEVs isolated from the plasma of controls, cholesteatoma-derived sEVs significantly enhanced keratinocyte proliferation and IL-6 production (p < 0.05), potentially by engaging multiple activation pathways including MAPKp44/p42, STAT3, and the NF-κB pathway. Thus, HMGB1(+) sEVs emerge as a novel factor potentially promoting cholesteatoma progression.

Experimental cholesteatoma: a comparison between spontaneous and induced models

OBJECTIVE

To compare the incidence and the histopathological aspect of spontaneous and two induced Mongolian gerbils' models of cholesteatoma: External Auditory Canal (EAC) obliteration model and the Auditory Tube (AT) cauterization model.

METHODS

Fifty-four ears of 27 animals were divided into EAC obliteration, AT cauterization, and control groups and histologically assessed for cholesteatoma incidence and classification at intervals of 2, 4, 8, and 16 weeks.

RESULTS

Cholesteatoma was diagnosed in 30 of the 53 ears evaluated with a significantly higher incidence in groups that received some type of intervention (p<0.0001). It was not possible to histologically distinguish cholesteatomas of the same stage between the study groups.

CONCLUSION

Although we observed a significant increase in cholesteatoma incidence with the two methods used when compared to the control group, all developed cholesteatomas were apparently identical from a histological point of view.

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.

Evaluation of bcl-2, bax and c-erbB-2 Levels in Chronic Otitis Patients with or without Cholesteatoma

Objective

The aim of this study was to evaluate bcl-2, bax, and c-erbB-2 expressions in primary and secondary acquired cholesteatoma and to indicate the role of apoptosis and accompanying increased cellular proliferation in the pathogenesis of cholesteatoma.

Methods

Samples obtained from the skin of the external ear canal (EEC) of patients operated for chronic otitis media (COM) without cholesteatoma constituted Group 1; samples from the EEC skin of patients in Group 3 operated for COM with cholesteatoma and from the EEC skin of patients in Group 4 constituted Group 2; samples obtained from the cholesteatoma matrix of patients operated for COM with primary acquired cholesteatoma constituted Group 3; and samples obtained from the cholesteatoma matrix of patients operated for COM with secondary acquired cholesteatoma constituted Group 4. The assessment of the positive cell ratio was based on the presence of the following findings and was semiquantitatively classified into four groups: 0, no staining; + cell staining (weak positive staining: 1%-33%); ++ cell staining (moderately positive staining: 34%-66%); and +++ cell staining (strong positive staining: 67%-100%).

Results

Comparison of the staining scores of bcl-2, bax, and c-erbB-2 revealed a statistically insignificant difference in the staining of samples obtained from the EEC skin (p>0.05). Decreased bcl-2 expression and increased bax and c-erbB-2 expressions were determined in primary and secondary acquired cholesteatoma epithelium compared with the EEC skin of patients operated for COM with or without cholesteatoma, and the differences were found to be statistically significant (p<0.05).

Conclusion

In acquired cholesteatoma epithelium, the finding of decreased bcl-2 expression as well as increased bax and c-erbB-2 expressions compared with the EEC skin is an indicator of the increase in both cellular proliferation and apoptosis.

Molecular signaling of the HMGB1/RAGE axis contributes to cholesteatoma pathogenesis

Abstract

Cholesteatoma represents progressive expansion of the keratinizing squamous epithelium in the middle ear with subsequent chronic inflammation in subepithelial connective tissues. The hypothesis was tested that receptor for advanced glycation endproduct (RAGE) and its ligand, high-mobility box 1 (HMGB1), are overexpressed in cholesteatoma, and the RAGE/HMGB1 axis might contribute to its pathogenesis. Cholesteatoma samples (n = 36) and 27 normal skin specimens were studied by immunohistochemistry (IHC) for HMGB1 and RAGE expression. Effects of HMGB1 signaling on proliferation, migration, cytokine production, and apoptosis of human immortalized keratinocytes (HaCaTs) and normal keratinocytes were studied by quantitative reverse transcription (qRT)-PCR, IHC, Western blots, and flow cytometry after cell co-incubation with HMGB1. While all studied tissues expressed HMGB1, its expression was higher in cholesteatoma than in normal skin (p < 0.0001). All cases of cholesteatoma also showed elevated RAGE expression levels, and only 7/27 (26 %) of normal skin specimens were weakly positive for RAGE. Proliferation and migration of HaCaT cells incubated with HMGB1 were up-regulated (p < 0.05). HMGB1 also prevented HaCaT cell apoptosis and induced activation of several molecular signaling pathways in keratinocytes. The data suggest that in cholesteatoma, HMGB1 released from stressed or necrotic epithelial cells and binding to RAGE overexpressed in keratinocytes initiates molecular signaling that culminates in pro-inflammatory cytokine release and chronic inflammation.

Key message

HMGB1 signaling engages multiple activation pathways in RAGE-positive keratinocytes.

HMGB1 protects RAGE-positive keratinocytes from drug-induced apoptosis.

Keratinocyte proliferation is controlled via RAGE and HMGB1 molecular signaling.

Molecular signaling of the HMGB1/RAGE axis contributes to cholesteatoma pathogenesis.

Electronic supplementary material

The online version of this article (doi:10.1007/s00109-014-1217-3) contains supplementary material, which is available to authorized users.

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.

Establishment of NOD/SCID mouse models of human hepatocellular carcinoma via subcutaneous transplantation of histologically intact tumor tissue

Hepatocellular carcinoma (HCC) is one of the most deadly human cancers, but it is very difficult to establish an animal model by using surgical specimens. In the present experiment, histologically intact fresh surgical specimens of HCC were subcutaneously transplanted in non-obese diabetic/severe combined immunodeficienccy (NOD/SCID) mice. The biological characteristics of the original and the corresponding transplanted tumors and cell lines were investigated. The results showed that 5 new animal models and 2 primary cell lines were successfully established from surgical specimens. Hematoxylin-eosin staining showed that xenografts retained major histological features of the original surgical specimens. The two new cell lines had been cultivated for 3 years and successively passaged for more than 100 passages in vitro. The morphological characteristics and biologic features of the two cell lines were genetically similar to the original tumor. The subcutaneous transplant animal models with histologically intact tumor tissue and primary cell lines could be useful for in vivo and in vitro testing of anti-cancer drugs and be ideal models to study various biologic features of HCC.

Role of Langerhans cells, Ki-67 protein and apoptosis in acquired cholesteatoma: prospective clinical study

OBJECTIVE

To investigate the role of Langerhans cells in the pathogenesis and clinical picture of middle-ear cholesteatoma.

SUBJECTS AND METHODS

The study included 40 patients operated upon for a diagnosis of chronic otitis due to acquired cholesteatoma.

RESULTS AND ANALYSIS

A closed surgical technique was used in 20 per cent of patients and an open technique in 80 per cent. Langerhans cells were more densely accumulated in cholesteatoma epithelium, compared with external ear canal skin (p < 0.001). Staining for Ki-67 protein was greater in cholesteatoma epithelium (p < 0.001) and Apo2.7 protein staining (indicating apoptosis) was more prominent (p < 0.001), compared with ear canal skin. Regarding significant relationships between clinical and pathological findings, staining for Ki-67 (p = 0.046) and Apo2.7 (p = 0.037) was more prominent in patients undergoing open versus closed surgery.

CONCLUSION

Using cell proliferation and apoptosis markers, a dense Langerhans cell infiltration was found to occur as a host response to middle-ear cholesteatoma.

Gerbils

The gerbil is usually nonaggressive and is one of the easiest rodents to maintain and handle. Its disposition, curious nature, relative freedom from naturally occurring infectious diseases, and adaptability to its environment have contributed to its popularity as a laboratory animal. Gerbils are found in deserts and semiarid geographical regions of the world. The Mongolian gerbils that are available today originated from 20 pairs of captured animals that were maintained in 1935 in a closed, random-bred colony at the Kitasato Institute in Japan. Gerbils have several unique anatomical and physiological features. Mature gerbils are smaller than rats, but larger than mice. Mongolian gerbils are attracted to saliva and use salivary cues to discriminate between siblings and nonsiblings, and females use oral cues in the selection of sociosexual partners. Gerbils have been used as experimental models in a number of areas of biomedical research. Gerbils are excellent subjects for laboratory animal research as they are susceptible to bacterial, viral, and parasitic pathogens that affect humans and other species. Gerbils may have spontaneous seizures secondary to stress such as handling, cage change, abrupt noises, or changes in the environment. Cystic ovaries are seen commonly in female gerbils over 1 year of age. Gerbils have unique characteristics, which make them appropriate for a number of animal models. Classically, gerbils have been used in research involving stroke, parasitology, infectious diseases, epilepsy, brain development and behavior, and hearing.

Animal models of middle ear cholesteatoma

Middle ear acquired cholesteatoma is a pathological condition associated with otitis media, which may be associated with temporal bone resorption, otorrhea and hearing loss, and occasionally various other complications. Cholesteatoma is characterized by the enhanced proliferation of epithelial cells with aberrant morphologic characteristics. Unfortunately, our understanding of the mechanism underlying its pathogenesis is limited. To investigate its pathogenesis, different animal models have been used. This paper provides a brief overview of the current status of research in the field of pathogenesis of middle ear acquired cholesteatoma, four types of animal models previously reported on, up-to-date cholesteatoma research using these animal models, our current studies of the local hybrid ear model, and the future prospect of new animal models of middle ear cholesteatoma.