Expression and Regulatory Mechanisms of MicroRNA in Cholesteatoma: A Systematic Review.

Cholesteatoma is a temporal bone disease characterized by dysfunctions of keratinocytes. MicroRNAs (miRNAs) are evolutionary conserved noncoding RNAs that regulate mRNA expression. They can be packaged into exosomes and transported to target cells that can be used in the future therapy of cholesteatoma. This study aimed to collect knowledge on the role of miRNAs and exosomal miRNAs in cholesteatoma and was conducted according to the PRISMA guidelines for systematic reviews. Four databases were screened: Pubmed/MEDLINE, Web of Science, Scopus, and the Cochrane Library. The last search was run on the 6th of June 2023. We included full-text original studies written in English, which examined miRNAs in cholesteatoma. The risk of bias was assessed using the Office of Health Assessment and Translation (OHAT) Risk of Bias Rating Tool, modified for the needs of this review. We identified 118 records and included 18 articles. Analyses revealed the downregulation of exosomal miR-17 as well as miR-10a-5p, miR-125b, miR-142-5p, miR34a, miR-203a, and miR-152-5p and the overexpression of exosomal miR-106b-5p as well as miR-1297, miR-26a-5p, miR-199a, miR-508-3p, miR-21-3p, miR-584-5p, and miR-16-1-3p in cholesteatoma. The role of differentially expressed miRNAs in cholesteatoma, including cell proliferation, apoptosis, the cell cycle, differentiation, bone resorption, and the remodeling process, was confirmed, making them a potential therapeutic target in this disease.

Cobalt chloride-stimulated hypoxia promotes the proliferation of cholesteatoma keratinocytes via the PI3K/Akt signaling pathway.

Herein, we purposed to explore whether hypoxia triggers proliferation of cholesteatoma keratinocytes via the PI3K-Akt signaling cascade. Cells were inoculated with different concentration of CoCl2. The proliferation and cellular HIF-1α, p-PDK1 and p­Akt expression levels of cholesteatoma keratinocytes were assessed in vitro. Hypoxia escalated cell proliferation via upregulating p-PDK1 and p­Akt expressions. Specific inhibitor of the PI3K-Akt signaling cascade, LY294002 markedly inhibited the expression of p­Akt and significantly reduces the hypoxia­induced proliferation of cholesteatoma keratinocytes. Our data provides research evidence confirming that hypoxia participates in the onset and progress of cholesteatoma.

Evaluation of significant gene expression changes in congenital and acquired cholesteatoma.

Etiopathogenesis of acquired and congenital cholesteatoma is still unclear. The clinical behavior of adult acquired, pediatric acquired and congenital cholesteatomas show differences. The scope of the this study was to detect the matrix metalloproteinase (MMP), tissue inhibitors of metalloproteinase (TIMP) and epidermal growth factor receptor (EGFR) gene expression changes in cholesteatoma perimatrix and to compare these changes among congenital cholesteatoma, adult acquired cholesteatoma and pediatric acquired cholesteatoma. A total of 16 genes including MMPs, TIMPs and EGFR were analyzed in the samples of 32 cholesteatoma tissues. Real-time PCR was used for detection of the gene expression levels. Data analyses were achieved by ΔΔCT method (Light Cycler 480 Quantification Software) and Statistical Package for Social Sciences (SPSS) version 22.0. The expression levels of MMP-2, -9, -10, -11, -13, -14, -15, -16 and EGFR genes were significantly higher in acquired cholesteatoma than healthy tissue (p < 0.05). There was a statistically significant decrease (3.34 times more) in the mean TIMP-2 gene expression level in acquired cholesteatoma compared to healthy tissue (p < 0.05). There was a significant increase in the mean expression level of MMP-7 gene and a decrease in the mean expression level of TIMP-1 gene (3.12 times more) in congenital cholesteatoma compared to healthy tissue (p < 0.05). This study indicates that increased expression levels of some particular MMP genes and EGFR gene and decreased expression levels of TIMP genes may play an important role in the development of cholesteatoma. Further, MMP-9, MMP-13 and MMP-14 genes may have a remarkable role in the development of more aggressive cholesteatoma forms. The authors concluded that overexpression of MMP-9, MMP-13 and MMP-14 may cause stronger inflammation associated with cholesteatoma.

Down-regulation of exosomal miR-106b-5p derived from cholesteatoma perimatrix fibroblasts promotes angiogenesis in endothelial cells by overexpression of Angiopoietin 2.

Human cholesteatoma perimatrix fibroblasts (hCPFs) can stimulate the endothelial cells of nearby microvessels to proliferate and migrate in a paracrine manner. Exosomes, secreted from various cell types, are one of the most important paracrine factors and play critical roles in intercellular communication. However, whether exosomes derived from human cholesteatoma perimatrix fibroblasts (hCPFs-Exo) can promote angiogenesis has not been reported. In this study, we isolated exosomes secreted by hCPFs and observed that hCPFs-Exo was able to promote migration and tube formation in human umbilical vein endothelial cells (HUVECs). Advanced studies revealed hCPFs-Exo with low expression of miR-106b-5p was transferred into HUVECs, and decreased expression of miR-106b-5p could promote angiogenesis by targeting Angiopoietin 2 (Angpt2) via binding to its 3'-UTR. Furthermore, low levels of miR-106b-5p triggered overexpression of Angpt2, and significantly increased HUVEC migration and tube formation. Taken together, our results suggest that hCPFs-Exo transports low expressed exosomal miR-106b-5p to endothelial cells and promotes angiogenesis by overexpression of Angpt2.

Comparative analysis of the expression of E-cadherin, ß-catenin, and ß1 integrin in congenital and acquired cholesteatoma.

E-cadherin, ß-catenin, and ß1 integrin are important cell adhesion molecules to maintain epithelial structure and function. We investigated the expression of these cell adhesion molecules in cholesteatomas to understand the role of cell-cell and cell-extracellular matrix interaction in cholesteatomas. An immunohistochemical investigation was carried out on 35 cholesteatoma tissue samples (14 congenital, 21 acquired cholesteatomas) and 10 normal retroauricular skin (RAS) tissues which are obtained during middle ear surgery. The expression rate was measured to find out differences between retroauricular skin and cholesteatoma, as well as between congenital and acquired cholesteatoma. E-cadherin expression rate was significantly lower in the cholesteatoma (spinous layer 88.7 ± 17.9 %, granular layer 54.6 ± 22.6 %) than in the RAS (100 %, 74.4 ± 7.4 %) and in the acquired (83.3 ± 19.4 %, 48.1 ± 22.9 %) than in the congenital (96.7 ± 12.0 %, 64.4 ± 18.8 %). ß-catenin expression rate was significantly lower in the cholesteatoma (spinous layer 84.1 ± 17.2 %, granular layer 28.7 ± 30.8 %) than in the RAS (100 %, 75.9 ± 6.1 %) and in the acquired (78.1 ± 17.0 %, 17.1 ± 22.3 %) than in the congenital (93.2 ± 13.5 %, 46.1 ± 34.2 %). The expression pattern of ß-catenin is similar to that of E-cadherin. In ß1 integrin, there was no significant difference of the expression rate between RAS and cholesteatoma, as well as between congenital and acquired cholesteatoma. In conclusion, the expression of E-cadherin and ß-catenin is reduced in cholesteatoma, and the reduction is more pronounced in acquired cholesteatoma than in congenital cholesteatoma. Acquired cholesteatomas showed more aggressive characteristics than congenital cholesteatomas in terms of cell-cell adhesion.

Cholesteatoma-associated fibroblasts modulate epithelial growth and differentiation through KGF/FGF7 secretion.

The keratinocyte growth factor (KGF/FGF7), produced by stromal cells, is a key paracrine mediator of epithelial proliferation, differentiation and migration. Expression of the growth factor is increased in wound healing and in hyperproliferative epithelial diseases, as a consequence of the activation of dermal fibroblasts by the inflammatory microenvironment. The middle ear cholesteatoma, an aural epidermal pathology characterized by keratinocyte hyperproliferation and chronic inflammation, may represent a model condition to study the epithelial-mesenchymal interactions. To develop an in vitro model for this disease, we isolated and characterized human primary cultures of fibroblasts associated with the cholesteatoma lesion, analyzing their secretory behaviour and degree of differentiation or activation. Compared to the perilesional or control normal fibroblasts, all cultures derived from cholesteatoma tissues were less proliferating and more differentiated and their highly variable activated phenotype correlated with the secretion of KGF as well as of metalloproteases 2 and 9. Culture supernatants collected from the cholesteatoma-associated fibroblasts were able to increase the proliferation and differentiation of human keratinocytes assessed by the expression of Ki67 and keratin-1 markers. The single crucial contribution of the KGF released by fibroblasts on the keratinocyte biological response was shown by the specific, although partial, block induced by inhibiting the KGF receptor or by immunoneutralizing the growth factor. Altogether, these results suggest that the activation of the stromal fibroblasts present in the pathological tissue, and the consequent increased secretion of KGF, play a crucial role in the deregulation of the epidermal proliferation and differentiation.

Expression of the receptor activator for nuclear factor-κB ligand and osteoprotegerin in chronic otitis media.

BACKGROUND: The receptor activator for nuclear factor-κB ligand (RANKL) and osteoprotegerin (OPG) are the key factors controlling the osteoclast and osteoblast action in the bone. PURPOSE: The study objective was to investigate the expression level of RANKL and OPG in cholesteatoma and granulation tissue, and to assess the relationship between their expression levels and osteolysis. MATERIAL AND METHODS: Patients with chronic otitis media with cholesteatoma (n = 28) and without cholesteatoma (n = 24) treated surgically at the Department of Otolaryngology of the Medical University of Gdansk were included in the study. RANKL and OPG expressions were analyzed by immunohistochemistry and Western blot. RESULTS: RANKL and OPG were expressed in all cholesteatoma and granulation tissues. RANKL expression was mainly observed in cholesteatoma subepithelial stroma, whereas OPG-positive cells originated from the epithelium. The number of OPG-positive cells in the normal skin was significantly higher than in cholesteatoma tissues. The RANKL protein level in cholesteatoma tissues was 1.8- and 1.5-fold higher than in the auditory canal skin and granulation tissues, respectively. The number of RANKL-positive cells in cholesteatoma tissues was significantly higher than in the normal skin. No substantial differences were found in average OPG protein levels between cholesteatoma tissues and the normal auditory canal skin. The ratio of RANKL/OPG was significantly higher in cholesteatoma tissues (2.93 ± 0.79) than in the skin samples (1.36 ± 0.34). CONCLUSIONS: Altered ratio of RANKL/OPG protein level in cholesteatoma tissues suggests that these proteins might be somehow involved in the pathogenesis of cholesteatoma. However, to resolve this issue a study on a larger group of patients should be conducted.

Relationship between clinicopathological characteristics and CYLD expression in patients with cholesteatoma.

Middle ear cholesteatoma is a destructive disease in which inflammation plays an important role in development and progression, and there are currently no biomarkers predicting prognosis or recurrence. Cylindromatosis (CYLD), a tumor suppressor deubiquitinase, serves as a negative regulator of inflammation expressed in tissues including the middle ear. To determine the clinical significance of CYLD in acquired cholesteatoma, we evaluated CYLD expression in acquired cholesteatoma tissue by immunostaining and analyzed its correlation with clinicopathological characteristics. Our immunohistochemical analysis revealed that CYLD expression levels were varied in the tissues of acquired cholesteatoma patients. The relative expression levels of CYLD in cholesteatoma exhibited a significant correlation with the grade of otorrhea (R = 0.532, p = 0.039). Moreover, the period of epithelialization was also significantly associated with the relative expression levels of CYLD (R = 0.720, p = 0.002). In addition, CYLD expression tended to be lower in the group with recurrence. These results suggest that low CYLD expression correlates with postoperative recovery of acquired cholesteatoma, while potentially affecting the induction of recurrence. This is the first report showing that low CYLD expression correlates with accelerated disease recovery, and suggests a new aspect of CYLD as a prognostic predictor of acquired cholesteatoma.

SEM BSE 3D Image Analysis of Human Incus Bone Affected by Cholesteatoma Ascribes to Osteoclasts the Bone Erosion and VpSEM dEDX Analysis Reveals New Bone Formation.

Bone erosion is considered a typical characteristic of advanced or complicated cholesteatoma (CHO), although it is still a matter of debate if bone erosion is due to osteoclast action, being the specific literature controversial. The purpose of this study was to apply a novel scanning characterization approach, the BSE 3D image analysis, to study the pathological erosion on the surface of human incus bone involved by CHO, in order to definitely assess the eventual osteoclastic resorptive action. To do this, a comparison of BSE 3D image of resorption lacunae (resorption pits) from osteoporotic human femur neck (indubitably of osteoclastic origin) with that of the incus was performed. Surface parameters (area, mean depth, and volume) were calculated by the software Hitachi MountainsMap© from BSE 3D-reconstructed images; results were then statistically analyzed by SPSS statistical software. Our findings showed that no significant differences exist between the two groups. This quantitative approach implements the morphological characterization, allowing us to state that surface erosion of the incus is due to osteoclast action. Moreover, our observation and processing image workflow are the first in the literature showing the presence not only of bone erosion but also of matrix vesicles releasing their content on collagen bundles and self-immuring osteocytes, all markers of new bone formation on incus bone surface. On the basis of recent literature, it has been hypothesized that inflammatory environment induced by CHO may trigger the osteoclast activity, eliciting bone erosion. The observed new bone formation probably takes place at a slower rate in respect to the normal bone turnover, and the process is uncoupled (as recently demonstrated for several inflammatory diseases that promote bone loss) thus resulting in an overall bone loss. Novel scanning characterization approaches used in this study allowed for the first time the 3D imaging of incus bone erosion and its quantitative measurement, opening a new era of quantitative SEM morphology.

Localisation of basic fibroblast growth factor in cholesteatoma matrix: an immunochemical study.

OBJECTIVE: To investigate the expression of basic fibroblast growth factor in the matrix of human acquired cholesteatoma compared to the deep meatal skin. This topic does not appear to have been fully investigated before. METHODS: An immunochemical study was conducted. Cholesteatoma tissues from adult patients were collected during surgery (n = 19). Control specimens were taken from the deep meatal skin (n = 8) and compared. RESULTS: A highly significant difference in basic fibroblast growth factor expression was identified between cholesteatoma and skin (mean ± standard error = 58.53 ± 3.6 per cent in cholesteatoma vs 40.6 ± 3.5 per cent in skin; p = 0.005). Both basal and parabasal keratinocytes were stained positive with basic fibroblast growth factor. Additionally, there was specific staining in the basal columnar middle-ear epithelium and mast cell membrane. CONCLUSION: Basic fibroblast growth factor plays an active role in proliferative activity of cholesteatoma through its overexpression in basal and parabasal layers of cholesteatoma matrix. Moreover, its expression in the mast cell membrane supports its role in bone resorption activity.

Predictive Role of Ki-67 and Proliferative-Cell Nuclear Antigen (PCNA) in Recurrent Cholesteatoma.

OBJECTIVES: To investigate the potential use of Ki-67 and pronuclear cell antigen (PCNA) as indicators of recurrent cholesteatoma. MATERIAL AND METHODS: Patients who had been diagnosed with cholesteatoma and who had undergone canal wall-down mastoidectomy were included in this study. Subjects were divided into two groups: recurrent and non-recurrent (i.e., cases without recurrence for at least 2 years). Ossicular pathologies were recorded. Histopathologic specimens were stained for Ki-67 and PCNA and the percentages of stained cells were calculated. RESULTS: Neither group demonstrated a significant difference in terms of total Ki-67 per cell, Ki-67-stained cell counts, Ki-67-staining percentages, total PCNA per cell, PCNA-stained cell counts, or PCNA-staining percentages (p>0.05). No significant relationship was noted between the staining percentages for either Ki-67 or PCNA and the incudostapedial involvement (p>0.05); however, a significant relationship was noted between Ki-67 staining and malleus involvement (p<0.05). CONCLUSION: Although the recurrent and non-recurrent cholesteatoma groups showed no significant differences in terms of the percentages of stained cells for either Ki-67 or PCNA, we detected high Ki-67 staining in the malleus involvement group. We concluded that cell-proliferation markers could not be defined as indicators of recurrence of cholesteatoma, but they could be defined as indicators of destructive patterns of this disease.

Partial Epithelial-Mesenchymal Transition Was Observed Under p63 Expression in Acquired Middle Ear Cholesteatoma and Congenital Cholesteatoma.

INTRODUCTION: Partial epithelial-mesenchymal transition (p-EMT) is a process by which epithelial cells partially lose their intercellular adhesion and change to obtain migration ability. The transcription factor p63 regulates the expression of cadherin family and induces epithelial cell proliferation. In this study, we hypothesized that p-EMT under p63 expression may be a key factor in epithelial cell growth in middle ear cholesteatoma. METHODS: Specimens were surgically excised from patients with congenital cholesteatoma (CC) (n = 48), acquired middle ear cholesteatoma (AC) (n = 120), and normal skin tissue (n = 34). We analyzed immunohistochemically for the EMT marker (N-cadherin), adherence junction marker (E-cadherin), and tight junction marker (claudin-1, claudin-4, occludin). We also examined the labeling index (LI) of p63 and Proliferating cell nuclear antigen (PCNA) (late S phase marker), and Snail expression as a mobility marker. RESULTS: The expression of p63 (CC 51.0 ±â€Š7.4%, AC 50.0 ±â€Š5.9%) was significantly higher in the thickened epithelium of CC and AC compared with normal skin tissue (p < 0.0001). The loss of E-cadherin was observed (CC 50.0%, AC 55.8%) but the expression patterns in the tight junction were almost normal. N-cadherin was partially detected in the basal and upper layer of epithelium in CC and AC. In contrast to that of normal skin tissue, the LI of PCNA was significantly higher in AC (p < 0.0001). The positive rate of Snail was significantly higher in CC (p < 0.0001). CONCLUSION: This study indicates that p-EMT via the p63 signaling pathway might plays an essential role in epithelial growth in AC and CC formation, although tight junction formation and terminal differentiation were not affected in those processes.

Comparison of changes in mitochondrial bioenergetics between keratinocytes in human external auditory canal skin and cholesteatomas from normoxia to hypoxia.

Cholesteatoma has attracted many studies seeking to uncover its nature and the pathogenesis of related diseases. However, no researchers have explored the mitochondrial bioenergetics of cholesteatoma. The aim of this study was to investigate the energy demand and differential mitochondrial respiration profiles between keratinocytes in external auditory canal (EAC) skin and cholesteatoma samples cultured in normoxic (20% O2) and hypoxic (5% O2) conditions. Enhanced cellular proliferation of both types of keratinocytes was found in hypoxia compared to normoxia. In 20% O2 conditions, cholesteatoma keratinocytes exhibited less mitochondrial mass, lower ATP levels, and significantly lower basal oxygen consumption rate (OCR) and reserve capacity compared to normal skin keratinocytes. In contrast, in hypoxic conditions, cholesteatoma keratinocytes showed markedly higher levels in maximal OCR and reserve capacity, as well as lower proton leak OCRs, compared to normal skin keratinocytes. Hypoxia induced the reverse mitochondrial bioenergy profile from that in normoxia between these two types of keratinocytes, implying that an adaptive change of mitochondrial respiration to oxygen fluctuations may develop in cases of cholesteatoma. Such adaptation in response to hypoxic conditions may play a role in explaining the pathogenesis of acquired cholesteatoma.

Analysis of KRT1, KRT10, KRT19, TP53 and MMP9 expression in pediatric and adult cholesteatoma.

Cholesteatoma is an epidermal cyst with still unknown pathomechanism. The aim of the current study was to investigate molecular differences in the background of the hyperproliferative property and aggressive behavior typical of the cholesteatoma epithelium. The expression of three cytokeratin genes (KRT1, KRT10 and KRT19), the matrix metalloproteinase 9 gene (MMP9) and the tumor suppressor TP53 gene was measured by qRT-PCR in surgical samples of pediatric and adult cholesteatoma cases and their expression level was compared to that of normal skin samples from the retroauricular region of control individuals. Cholesteatoma samples were stratified according to the age of onset and recurrence for more detailed analysis. Our results showed identical expression pattern for KRT1 and KRT10, their expression was higher in pediatric cases than in adults, especially in pediatric recurrent samples. The expression level of KRT19 was inversely proportional to that of KRT1/KRT10, it was lower in the more invasive recurrent cases both in our pediatric and adult groups. As it was expected from the bone destructive behavior of cholesteatoma, a significantly elevated expression of MMP9 was measured in cholesteatoma samples, the highest level was found in adult recurrent cases. Low expression levels characterize the TP53 gene without significant differences in our samples. These findings demonstrate that cytokeratin expression distinguishes between pediatric/adult, nonrecurrent/recurrent cases, suggesting that distinct differentiation state and cell division potential characterize these cholesteatoma cases. KRT19 with a tumor suppressor potential might restrict the recurrence of cholesteatoma. The differences observed in gene expression profiles between cholesteatoma and control samples support the notion that cholesteatoma is a cystic lesion with tumor-like behavior because it is characterized by invasive, destructive growth and high tendency for recurrence.

Sulindac sulfone modulates beta-catenin in human cholesteatoma cell culture.

BACKGROUND: External auditory canal cholesteatoma (EACC) is a chronic inflammation of the bony ear meatus. Its etiology is not clearly understood. Other than surgical intervention, conservative methods are investigated for different cholesteatomas. Inducing apoptosis seems to be an appropriate strategy. Sulindac sulfone is a new class of targeted and pro-apoptotic drugs. It provokes apoptosis by inducing phosphorylation of beta-catenin, which is a multifunctional protein in the cell-cell adhesion complex. METHODS: EACC-cell cultures were incubated with different concentrations of sulindac sulfone (400 and 800 micromol). After 16, 24, and 48 h, beta-catenin concentrations were determined by ELISA, Western blot, and immunohistochemical analysis. RESULTS: After 48 h incubation with 400 micromol sulindac sulfone, the average level of beta-catenin showed a decrease of 46% (0.004337 microg/mL) from those determined at 16 h with the same concentration of sulindac sulfone. At 800 micromol sulindac sulfone, the treated cell culture showed a reduction of 66.2% (0.003443 microg/mL). Comparing total protein content and the fraction of beta-catenin at different points in time, the concentration of beta-catenin decreased in both EACC cell cultures, 400 micromol (minus 63%) and 800 micromol (minus 81%). CONCLUSIONS: The results presented in this paper are the first to demonstrate the chemopreventive effects of the agent sulindac sulfone on cholesteatomas. The greatest decrease of beta-catenin was observed between 16 and 24 h incubation. The inhibitory effect of sulindac sulfone as a local treatment seems to be a useful additional tool for nonsurgical approach to the therapy of EACCs.

Catabolism of glycoconjugates in chronic otitis media with cholesteatoma.

Chronic ear disease with cholesteatoma is characterized by an intrusion of keratinizing stratified squamous epithelium into the middle ear manifesting bone resorption at the interface of the perimatrix. The aim of our study was to investigate the markers of a catabolic process associated with several chronic inflammatory states. We assessed the level of catabolism of glycoconjugates in assays of cholesteatoma extracts, quantifying two lysosomal exoglycosidases: alpha-mannosidase (alpha-MAN) and beta-galactosidase (beta-GAL). Cholesteatomas (n = 15) and normal adult postauricular skin served as controls (n = 15) were collected from the patients during surgery owing to chronic otitis media. To assess exoglycosidase activity, release of p-nitrophenol from p-nitrophenol derivatives of alpha-mannose and beta-galactose was used. In 13 of 15 specimens, we observed significantly higher activity of investigated enzymes in cholesteatoma tissue compared with control tissue (postauricular skin). The mean activity of alpha-MAN from the cholesteatoma cells was 1.76 +/- 1.10 nkat/g wet tissue and 0.61 +/- 0.21 nkat/g wet tissue in the control probes. The mean activity of beta-GAL from the cholesteatoma cells was 1.77 +/- 1.07 nkat/g wet tissue and 0.87 +/- 0.20 nkat/g wet tissue in the control probes. Catabolic reactions involving glycoproteins, glycolipids, and proteoglycans may play a role in cholesteatoma-related bone resorption. The present data indicating that the lysosomal exoglycosidases alpha-MAN and beta-GAL are significantly and consistently elevated suggest the need to further correlations assessment between levels of alpha-MAN and beta-GAL and cholesteatoma behavior. Further research should also evaluate the relative importance of these particular exoglycosidases in manifesting bone resorption in considering the spectrum of identified inflammatory mediators.

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

INTRODUCTION: Cholesteatoma is a benign tumor of the middle ear characterized by an aggressive and invasive potential. The only current treatment being surgery, it is important to have access to a reliable animal model to study and better understand cholesteatoma pathogenesis. Our study aimed to examine the biological validity of the most common experimental model of cholesteatoma: the Mongolian gerbil. MATERIAL AND METHODS: We have induced cholesteatoma by surgical ligature of the gerbil's external auditory duct. Quantitative comparison of eight biological markers involved in inflammation (macrophage migration inhibitory factor [MIF]), cell differentiation (retinoic acid receptors-alpha, -beta, and -gamma), and cell adhesion/apoptosis (galectins-1, -3, -7, and -8). The immunohistochemical staining was quantified by computer-assisted microscopy. RESULTS: Two immunohistochemical parameters were determined in sections. The labeling index (LI) represents the percentage of tissue area specifically stained, and the mean optical density (MOD) denotes the staining intensity index. The LI reveals statistically significant differences for each marker tested. The MOD also shows statistically significant differences except for MIF (P = .259). CONCLUSION: From the panel of markers, the majority of staining parameters was statistically significantly different between sections of the animal model and clinical specimen. These data do not support the concept of complete validity of the popular animal model.

Keratinocyte growth factor and its receptor expression in chronic otitis media with and without cholesteatoma.

INTRODUCTION: Chronic suppurative otitis media (CSOM) with and without cholesteatoma is regarded as chronic inflammation of the middle ear and mastoid mucosa that can be associated with the presence of granulation tissue and infection, which can lead to ossicular damage and hearing loss, but it is commonly known that cholesteatoma behaves aggressively. Both lesions appear to contain a predominant population of inflammatory cells, among which proinflammatory cytokines secreting keratinocyte growth factor (KGF) and its receptor (KGFR). No clear difference was demonstrated between these entities. The purpose of this study was to investigate the potential influence of KGF and KGFR in increased epithelial-cell proliferation of chronic otitis media (COM) with cholesteatoma in contrast to COM without cholesteatoma (CSOM), particularly in the granulative form, and to compare the rate of proliferation activity of epithelial cells using the Ki-67 epithelial proliferation marker expression. PATIENTS, MATERIALS AND METHODS: We analyzed 105 ears with cholesteatoma vs. 53 ears with CSOM without cholesteatoma using our KGF and KGFR variables, and the ratio of proliferating epithelial cells using Ki-67. The percentage of the specimens expressing KGF and KGFR was compared between the two groups for statistical significance using the Pearson's chi-square test. Immunohistochemical staining was conducted and the proportion of the cells staining positive for the nuclear antigen Ki-67 was evaluated in a quantitative and visual way, using light microscopes. RESULTS: KGF was positive in 88.57% of cholesteatoma and was positive in 41.51% CSOM without cholesteatoma specimens (cholesteatoma vs. CSOM, p=0.001). The positive rate of KGFR in the CSOM group was 33.96% compared to those in cholesteatoma, which was 60.95%. Compared to the cholesteatoma specimens, a significantly smaller number of Ki-67 labeling index was detected in CSOM specimens. CONCLUSIONS: Our results indicated that the abnormal behavior of the cholesteatoma epithelium seems to be induced by the paracrine interaction between KGF and KGFR. Furthermore, we found that cholesteatoma expressing both KGF and KGFR had high Ki-67 index, which correlated with its aggressiveness. These findings suggest that excessive KGF and KGFR synthesis may contribute to the hyperproliferative state in cholesteatoma and could explain the pathological difference between cholesteatoma and CSOM.

The role of S100A1 in external auditory canal cholesteatoma.

S100 proteins were reported to be involved in different biological activities such as transduction of intracellular calcium signalling. It has been reported that each member of the S100 protein family exhibits a distinct tissue-specific pattern of expression. Furthermore, altered S100 protein expression and function correlate with many diseases. The expression of S100A1 was reported to be increased in different tissue with hyperplasia. The external auditory canal cholesteatoma (EACC) is a benign hyperplasia of the auditory meatal skin. However, without treatment, EACC destroys adjacent tissue. Seventeen EACC specimens were collected and investigated immunohistochemically against S100A1. Normal auditory meatal skin served as control. In the EACC, S100A1 showed a more homogeneous staining pattern, positively expressed throughout the epithelial layers. The keratin debris showed no detectable expression of S100A1. In the auditory meatal skin (control), S100A1 was only expressed in the basal layer of the epithelium. We showed that there are different staining patterns in normal auditory meatal skin, middle ear cholesteatoma and external auditory canal cholesteatomas. The immunoreactivity increased with the stage of the disease. Contrary to that reported previously in the middle ear cholesteatomas, the reactivity was strongest in the upper epithelial layers. In our collective, the epithelial matrix of the EACC showed strong reactivity throughout all the layers. Surprisingly, there is no study regarding the connection between growth factors and S100A1. In previous experiments we showed significant increase of growth factors in EACC. This correlates with our new data concerning S100A1. This is the first study to show the different reactivity pattern of S100A1 in the external auditory canal cholesteatoma.

Intercellular Communication between Keratinocytes and Fibroblasts Induces Local Osteoclast Differentiation: a Mechanism Underlying Cholesteatoma-Induced Bone Destruction.

Bone homeostasis is maintained by a balance in activity between bone-resorbing osteoclasts and bone-forming osteoblasts. Shifting the balance toward bone resorption causes osteolytic bone diseases such as rheumatoid arthritis and periodontitis. Osteoclast differentiation is regulated by receptor activator of nuclear factor κB ligand (RANKL), which, under some pathological conditions, is produced by T and B lymphocytes and synoviocytes. However, the mechanism underlying bone destruction in other diseases is little understood. Bone destruction caused by cholesteatoma, an epidermal cyst in the middle ear resulting from hyperproliferation of keratinizing squamous epithelium, can lead to lethal complications. In this study, we succeeded in generating a model for cholesteatoma, epidermal cyst-like tissue, which has the potential for inducing osteoclastogenesis in mice. Furthermore, an in vitro coculture system composed of keratinocytes, fibroblasts, and osteoclast precursors was used to demonstrate that keratinocytes stimulate osteoclast differentiation through the induction of RANKL in fibroblasts. Thus, this study demonstrates that intercellular communication between keratinocytes and fibroblasts is involved in the differentiation and function of osteoclasts, which may provide the molecular basis of a new therapeutic strategy for cholesteatoma-induced bone destruction.