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.

Hsa_circ_0074491 regulates the malignance of cholesteatoma keratinocytes by modulating the PI3K/Akt pathway by binding to miR-22-3p and miR-125a-5p: An observational study.

ABSTRACT: Cholesteatoma is a benign cystic lesion that can continue to grow like a tumor. Circular ribonucleic acid (RNA) hsa_circ_0074491 (circ_0074491) has been reported to be down-regulated in cholesteatoma tissues. However, the role and regulatory mechanism of circ_0074491 in the growth of cholesteatoma are unclear.The expression of circ_0074491, microRNA (miR)-22-3p, and miR-125a-5p in cholesteatoma tissues was detected by quantitative real-time polymerase chain reaction. The proliferation, cell cycle, apoptosis, migration, and invasion of cholesteatoma keratinocytes were evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, plate clone, flow cytometry, or transwell assays. Several protein levels were examined by western blotting. The targeting relationship between miR-22-3p or miR-125a-5p and circ_0074491 was verified via dual-luciferase reporter and RNA pull-down assays.We observed the downregulation of circ_0074491 in cholesteatoma tissues. Furthermore, circ_0074491 knockdown facilitated cell proliferation, migration, invasion, and repressed cell apoptosis in cholesteatoma keratinocytes. Circ_0074491 was verified as a decoy for miR-22-3p and miR-125a-5p in cholesteatoma keratinocytes. Both miR-22-3p and miR-125a-5p silencing reversed the impacts of circ_0074491 silencing on proliferation, apoptosis, migration, and invasion of cholesteatoma keratinocytes. Also, circ_0074491 knockdown activated the PI3K/Akt pathway in cholesteatoma keratinocytes via miR-22-3p and miR-125a-5p.Circ_0074491 played a suppressive role in cholesteatoma through inactivating the PI3K/Akt pathway via binding to miR-22-3p and miR-125a-5p, which provided a novel evidence for the involvement of circRNA in the development of cholesteatoma.

Cytokine secretion and pyroptosis of cholesteatoma keratinocytes mediated by AIM2 inflammasomes in response to cytoplasmic DNA.

Cholesteatoma constitutes an acquired benign epidermal non­permanent bone lesion that is locally destructive and patients often relapse. Inflammasomes, which mediate the maturation and production of IL­18 and IL­1ß, resulting in pyroptosis, have been documented to serve a core function in multiple inflammatory conditions. Absent in melanoma 2 (AIM2) is an inflammasome that identifies cytoplasmic DNA and has previously been reported as a pivotal modulator of inflammatory responses. Therefore, the present study aimed to determine the expression levels of AIM2 in human cholesteatoma tissues, and elucidate its function in modulating cytokine production. The expression levels of IL­18, apoptosis­associated speck­like protein containing a CARD (ASC), IL­1ß, AIM2 and caspase­1 were markedly elevated in cholesteatoma tissues. Protein expression levels of AIM2, caspase­1 and ASC were localized in the cellular cytoplasm, primarily in the granular and prickle­cell layers in the cholesteatoma epithelium. Induction using IFN­Î³, as well as cytoplasmic DNA markedly activated the AIM2 inflammasome and elevated the release of IL­18 and IL­1ß in human cholesteatoma keratinocytes. IFN­Î³ was found to enhance poly(dA:dT)­induced pyroptosis of cells and cytokine production. The results of the present study revealed that AIM2 expressed in human cholesteatoma serves a vital function in the inflammatory response by initiating the inflammasome signaling cascade in 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.

Stem Cell-Induced Inflammation in Cholesteatoma is Inhibited by the TLR4 Antagonist LPS-RS.

Cholesteatoma is a severe non-cancerous lesion of the middle ear characterized by massive inflammation, tissue destruction, and an abnormal growth of keratinized squamous epithelium. We recently demonstrated the presence of pathogenic stem cells within cholesteatoma tissue, unfortunately their potential roles in regulating disease-specific chronic inflammation remain poorly understood. In the presented study, we utilized our established human in vitro cholesteatoma stem cell model for treatments with lipopolysaccharides (LPS), tumor necrosis factor α (TNFα), and the TLR4-antagonist LPS from R.sphaeroides(LPS-RS) followed by qPCR, western blot, and immunocytochemistry. Middle ear cholesteatoma stem cells (ME-CSCs) showed a significantly increased expression of TLR4 accompanied by a significantly enhanced LPS-dependent pro-inflammatory gene expression pattern of TNFα, IL-1α, IL-1ß, IL-6, and IL-8 compared to non-pathogenic control cells. LPS-dependent pro-inflammatory gene expression in ME-CSCs was driven by an enhanced activity of NF-B p65 leading to a TNFα-mediated feed-forward-loop of pro-inflammatory NF-B target gene expression. Functional inactivation of TLR4 via the TLR4-antagonist LPS-RS blocked chronic inflammation in ME-CSCs, resulting in a nearly complete loss of IL-1ß, IL-6, and TNFα expression. In summary, we determined that ME-CSCs mediate the inflammatory environment of cholesteatoma via TLR4-mediated NF-B-signaling, suggesting a distinct role of ME-CSCs as drivers of cholesteatoma progression and TLR4 on ME-CSCs as a therapeutic target.

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.

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.

Are human ATP-binding cassette transporter C11 and earwax associated with the incidence of cholesteatoma?

Cholesteatoma is an ear disease based on a locally destructive noncancerous conglomerate of epidermis and keratin debris. Abnormal growth of stratified keratinized squamous epithelium in the temporal bone causes destruction of the outer and middle ear, potentially leading to hearing impairment, facial palsy, vertigo, lateral sinus thrombosis, and intracranial complications. Although cholesteatoma is effectively treated by surgical resection (mastoidectomy), the lack of effective and nonsurgical therapies potentially results in fatal consequences, establishing the need for a comprehensive investigation of cholesteatoma pathogenesis. Although its etiology is still being debated, interestingly, we found that the trend associated with the 538G allele frequency of the adenosine triphosphate-binding cassette transporter C11 (ABCC11) gene, the determinant of wet-type earwax, and ethnic groups was similar to that between the incidence of cholesteatoma and ethnic groups (countries). The incidences of cholesteatoma in Europe (Denmark, Finland, and Scotland) are higher than in East Asia (Japan), and the frequencies of the ABCC11 538G allele in African, American, and European (Finland and Scotland) populations are higher than those in East Asian populations (Japan). Additionally, a single-nucleotide polymorphism in the ABCC11 gene (rs17822931, 538G > A; Gly180Arg) is closely related to earwax morphotypes. While earwax is often beneficial to ear health, it is sometimes harmful in cases where it causes hearing impairment. Based on independent findings of associations between ABCC11 and the physiological environment of the auditory canal, we hypothesize a possible link between ABCC11, earwax, and the incidence of cholesteatoma.

Downregulation of MiR-203a Disinhibits Bmi1 and Promotes Growth and Proliferation of Keratinocytes in Cholesteatoma.

Background: Keratinocytes are the predominant cell type in a cholesteatoma, and microRNA (miR)-203a has been shown to be essential for the growth and differentiation of keratinocytes. The regulatory mechanisms of miR-203a and Bmi1-the predicted target of miR-203a that is associated with cholesteatoma-have not been clarified. Methods: Real-time PCR and western blot were carried out for the detection of miRNAs, mRNAs, and proteins, including miR-203a, Bmi1, and phosphorylated (p-)Akt. Immunohistochemical staining was applied to observe the expression and distribution of Bmi1 and of p-Akt in cholesteatoma and in control retroauricular skin. The dual luciferase reporter assay was used to analyze the relationship between miR-203a and Bmi1. Ectopic miR-203a and Bmi1 were transfected into an immortalized line of human keratinocytes (HaCaT cells), and the roles of these molecules in cell proliferation, apoptosis, and migration were explored. Results: Cholesteatoma tissues were characterized by downregulation of miR-203a and concomitant upregulation of Bmi1. Results of the dual-luciferase reporter assay indicated that Bmi1 was a direct target gene of miR-203a. Silencing of miR-203a increased Bmi1 expression; promoted proliferation, colony formation, and migration of HaCaT cells; and inhibited apoptosis. Moreover, p-Akt was significantly increased in cholesteatoma tissues and was positively correlated with Bmi1. Suppression of Bmi1 reduced p-Akt expression in HaCaT cells; subsequent inhibition of miR-203a reversed this phenomenon. Conclusions: Our results reveal that miR-203a may regulate cholesteatoma growth and proliferation by targeting Bmi1. These findings provide insight for the development of novel nonsurgical options for cholesteatoma.

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.

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.

NOD-Like Receptor Signaling in Cholesteatoma.

Background. Cholesteatoma is a destructive process of the middle ear resulting in erosion of the surrounding bony structures with consequent hearing loss, vestibular dysfunction, facial paralysis, or intracranial complications. The etiopathogenesis of cholesteatoma is controversial but is associated with recurrent ear infections. The role of intracellular innate immune receptors, the NOD-like receptors, and their associated signaling networks was investigated in cholesteatoma, since mutations in NOD-like receptor-related genes have been implicated in other chronic inflammatory disorders. Results. The expression of NOD2 mRNA and protein was significantly induced in cholesteatoma compared to the external auditory canal skin, mainly located in the epithelial layer of cholesteatoma. Microarray analysis showed significant upregulation for NOD2, not for NOD1, TLR2, or TLR4 in cholesteatoma. Moreover, regulation of genes in an interaction network of the NOD-adaptor molecule RIPK2 was detected. In addition to NOD2, NLRC4, and PYCARD, the downstream molecules IRAK1 and antiapoptotic regulator CFLAR showed significant upregulation, whereas SMAD3, a proapoptotic inducer, was significantly downregulated. Finally, altered regulation of inflammatory target genes of NOD signaling was detected. Conclusions. These results indicate that the interaction of innate immune signaling mediated by NLRs and their downstream target molecules is involved in the etiopathogenesis and growth of cholesteatoma.

MicroRNA let-7a suppresses the growth and invasion of cholesteatoma keratinocytes.

Cholesteatomas are benign epidermally­derived lesions of the temporal bone that are caused by migration of hyperproliferative keratinocytes into the middle ear and mastoid cavity. The molecular mechanisms that regulate the pathogenesis of cholesteatomas are currently not fully understood. The present study demonstrated the antigrowth and anti­invasive effects of let­7a microRNA (miRNA) on cholesteatoma keratinocytes. Let­7a inhibited the growth of cholesteatoma keratinocytes through two different mechanisms: Restriction of the proliferation of keratinocytes by promoting cell cycle arrest in the G0/G1 phase, and the induction of apoptosis of the cells. In addition to its role in the inhibition of cell growth, let­7a suppressed the migration and invasion of cholesteatoma keratinocytes. A mechanistic study showed that let­7a downregulated the expression of miR­21. Considering the function of miR­21 in the regulation of proliferation and apoptosis, let­7a may control cell proliferation and apoptosis by regulating miR­21, and its targets, in cholesteatoma keratinocytes. In conclusion, the present study showed that let­7a downregulates the expression of miR­21, resulting in the suppression of proliferation and induction of apoptosis. The results of the present study reveal the crucial role of let­7a miRNA in the inhibition of growth and invasion of cholesteatoma keratinocytes.

Induction of cytokine production in cholesteatoma keratinocytes by extracellular high-mobility group box chromosomal protein 1 combined with DNA released by apoptotic cholesteatoma keratinocytes.

High-mobility group box chromosomal protein 1 (HMGB-1), a nuclear DNA binding protein, was recently rediscovered as a new proinflammatory cytokine. The purpose of this study was to determine HMGB-1 expression in vivo and to identify the effect of extracellular HMGB-1 in inflammatory process associated with bone destruction in cholesteatoma. We investigated the expression and location of HMGB-1 in the cholesteatoma and healthy skin using an immunofluorescence assay. We also detected apoptosis and DNA fragments in the cholesteatoma by TUNEL staining. HMGB-1 concentration in apoptotic supernatants from UV light-treated cells, culture supernatants and its translocation in cholesteatoma keratinocytes stimulated by supernatants from UV light-treated cells were measured by immunoblot analysis and immunofluorescence assay. Cultures of human cholesteatoma keratinocytes were exposed to CpG-DNA, HMGB-1, or CpG-DNA complexed to HMGB-1 for 24 h. Cytokines in the culture supernatant were measured by ELISA. In addition, levels of proinflammatory cytokines released by cholesteatoma keratinocytes stimulated by supernatants from UV light-treated cells with or without anti-HMGB-1 antibodies and supernatants from UV light-treated cells with DNase 1 were measured by enzyme-linked immunosorbent assay. The expression of HMGB-1 in cholesteatoma increased and it translocated both to the cytoplasm and extracellular space. Furthermore, the HMGB-1 concentration in supernatants increased significantly after addition of supernatants from UV light-treated cells. TNF-α and IL-1ß can be induced by purified HMGB-1 combined with CpG-DNA in the cholesteatoma keratinocytes. In addition, supernatants of apoptotic cells containing HMGB-1-DNA were effective in inducing TNF-α and IL-1ß secretion. This study suggested that persistent expression of extracellular HMGB-1 and DNA fragments in cholesteatoma leads to TNF-α and IL-1ß production, causing bone resorption and destruction. Thus, we have implicated that HMGB-1-DNA complexes might act as a key molecule involved in bone resorption associated with cholesteatoma.

Cathelicidin antimicrobial peptide LL-37 in cholesteatoma enables keratinocyte reactivity with cytosolic DNA.

The purpose of this study was to determine whether self-DNA can trigger the inflammatory response in cholesteatoma. Specimens were collected from nine patients with invasive cholesteatoma, nine patients with attic-type cholesteatoma (pars flaccida was perforated in five patients and intact in four) and four healthy skins. Expression and localization of LL-37 and interferon-alpha were detected by immunofluorescence and immunoblot analysis. Cultures of human cholesteatomatous keratinocytes were exposed to CpG DNA, LL-37 or CpG DNA complexed to LL-37 for 24 h. Expression of interferon-alpha was detected by RT-PCR. We detected abundant cytosolic DNA, increased LL-37 and interferon-alpha in keratinocytes in invasive cholesteatoma and attic-type cholesteatoma with pars flaccida perforation, but not in attic-type cholesteatoma with pars flaccida intact and normal skin. In cultured keratinocytes, LL-37-DNA complexes induced IFN-α expression. These data suggest that cytosolic DNA is an important disease-associated molecular pattern that triggers the inflammation response in cholesteatoma. Furthermore, LL-37 played an important role in DNA-triggered inflammation. Thus, we have identified a link between cytosolic DNA, LL-37 and autoinflammation in cholesteatoma, providing new potential targets for the treatment of this disease.

Congenital cholesteatoma in siblings.

INTRODUCTION: The exact aetiology of congenital cholesteatoma, the less common form of this destructive disease, is still under debate. CASE REPORT: A two-year-old boy was referred to paediatric otolaryngology with persistent, bloody, left-sided otorrhoea refractory to oral and ototopical antibiotics. Prior to its onset at age 16 months, all ear examinations on the affected side were normal. Physical examination, imaging with computed tomography and eventual tympanomastoidectomy revealed extensive cholesteatoma. The extent of the disease, age at onset of symptoms and absence of otological disease before initial presentation suggested the diagnosis of congenital cholesteatoma. Review of the family history revealed that the patient's older brother had undergone tympanomastoidectomy for a small, well-encapsulated, mesotympanic congenital cholesteatoma at two years of age. DISCUSSION: This case joins a single, previous report describing congenital cholesteatoma in multiple family members, suggesting that in some cases, hereditary factors may play a role in the formation of the disease.

Congenital cholesteatoma and cochlear implantation: Implications for management.

INTRODUCTION: Cholesteatoma is an uncommon condition that has occasionally been associated with cochlear implantation (CI). Cases of secondary acquired cholesteatoma have been described, in which intra-operative breech of the posterior canal wall is thought to be a contributing factor. Primary acquired cholesteatoma is not typically associated with congenital sensorineural hearing loss (SNHL) or CI in children. Congenital cholesteatoma is a rarer entity yet with an incidence in the literature of 2­4% of all cholesteatomas. We present lessons learned from our experience of congenital cholesteatoma in CI candidates. METHODS: Retrospective reviews of departmental CI and cholesteatoma databases in a tertiary/quaternary pediatric center were conducted. Cases of congenital cholesteatoma were identified. The proportion of congenital cholesteatoma cases in CI candidates was compared with number of acquired cholesteatoma. Optimum management of congenital cholesteatoma in CI candidates was reviewed. RESULTS: In our pediatric CI population, 2/794 patients (0.25%) were recognized as having a congenital cholesteatoma during their evaluation for CI. No cases of primary acquired cholesteatoma were identified in this population at presentation or at follow up to 18 years. DISCUSSION: The 0.25% incidence of congenital cholesteatoma in our population of CI patients is higher than expected of this rare condition. It is surprisingly common given the absence of any cases of primary acquired cholesteatoma, which is considerably more common even in the pediatric population. Both patients likely had an inherited form of hearing loss and a genetic contribution to the presence of congenital cholesteatoma cannot be excluded. The presence of congenital cholesteatoma has implications for the algorithm currently employed for the assessment of CI. We consider that surgery should be staged to ensure complete removal of the cholesteatoma before implantation. Thus bilateral CI should be provided sequentially rather than simultaneously in the presence of unilateral cholesteatoma.

Post-transcriptional regulation by microrna-21 and let-7a microRNA in paediatric cholesteatoma.

This study investigated the role of microRNA-21 (miR-21) and let-7a microRNA in paediatric and adult cholesteatoma. Total RNA and protein were isolated from the cholesteatoma specimens and normal skin of 10 adults and 10 children. Levels of miR-21 and let-7a microRNA were assessed by real-time reverse transcription-polymerase chain reaction, and levels of phosphatase and tensin homologue (PTEN), programmed cell death 4 (PDCD4) and high mobility group AT-hook 2 (HMGA2) protein were assessed by Western blot analysis. Levels of miR-21 and let-7a microRNA were significantly higher in cholesteatoma tissue compared with normal skin, especially in paediatric patients. PTEN, PDCD4 and HMGA2 protein levels were significantly lower in paediatric versus adult cholesteatoma patients. It is possible that upregulation of miR-21 leads to higher tumour cell proliferation and invasion of cholesteatoma in children than adults, and the benign nature of cholesteatoma may be due to a balance between let-7a microRNA and miR-21. These data may help to identify targets for miRNA- and protein-based therapeutic interventions for the non-surgical or adjunctive treatment of cholesteatoma.

Increased amphiregulin expression as a biomarker of cholesteatoma activity.

OBJECTIVES/HYPOTHESIS: The purpose of this study was to evaluate human surgical specimens for cholesteatoma-associated changes in amphiregulin expression and determine potential relations to clinical disease variables. Amphiregulin, an epidermal growth factor receptor ligand, has functions in normal epithelial proliferation and aberrant neoplastic cell growth and is proinflammatory (e.g., rheumatoid arthritis, fibrosis) and active in hyperproliferative cutaneous conditions including psoriasis and wound healing. These known amphiregulin activities and the characteristic epithelial expansion and bone erosion of cholesteatoma pathophysiology prompted testing of the hypothesis that amphiregulin expression levels are altered in cholesteatoma and correlate to the disease state. STUDY DESIGN: Prospective experimental study, cross-sectional analysis. METHODS: Relative changes in amphiregulin gene expression were quantitated by real-time reverse-transcription polymerase chain reaction analyses of cholesteatoma epithelium compared to uninvolved control tissues from patients' postauricular and external auditory canal regions. Western immunoblot assays were performed for qualitative evaluation of amphiregulin protein expression. The t test and Fisher exact test were used for analysis. RESULTS: A statistically significant increase in amphiregulin gene expression was associated with cholesteatoma specimens compared to uninvolved postauricular skin (PAS) and external auditory canal (EAC) skin, P = .004 and P = .002, respectively. From comparisons of 60 sets of skin pairs, the mean ratio of amphiregulin RNA expression for cholesteatoma/PAS is 4.94 (standard error of the mean [SEM] = 1.53, n = 30) and for cholesteatoma/EAC is 7.70 (SEM = 1.57, n = 30). CONCLUSIONS: Amphiregulin is overexpressed in epithelial tissues of human cholesteatoma. Significant relationships were identified between increased amphiregulin expression levels and the extent of cholesteatoma migration and bone erosion. Our study results indicate amphiregulin is a potential biomarker of early cholesteatoma disease processes.

Pediatric cholesteatoma and variants in the gene encoding connexin 26.

OBJECTIVES/HYPOTHESIS: Connexin 26 is a gap junction protein encoded by the GJB2 gene. It is expressed in cholesteatoma, and mutations cause proliferative skin disorders and sensorineural hearing loss (SNHL). Deletions of GJB6, which encodes connexin 30, cause SNHL in a digenic manner with a heterozygous GJB2 mutation. We hypothesize that GJB2 and GJB6 mutations might influence the development of cholesteatoma. STUDY DESIGN: Prospective observational study to identify GJB mutations in pediatric cholesteatoma. METHODS: Peripheral blood samples from 98 children with cholesteatoma were screened for mutations in the GJB2 gene by direct sequencing of the coding region (exon 2 and the intron/exon boundary). Deletions of the GJB6 gene were tested using multiple ligation probe amplification methods. GJB status was compared with other populations and patient age and extent of cholesteatoma at presentation. RESULTS: Fourteen children had at least one GJB2 variant (14%). Of these, three had two variants. Two of the variants were neutral polymorphisms. One child with the GJB2 genotype 35delG/35delG also had SNHL. No correlation was found between GJB2 status and patient age or cholesteatoma severity at presentation. No GJB6 deletions were found. CONCLUSIONS: GJB2 gene variants are present in a minority of children with cholesteatoma, but may be more common than in normal populations. It is conceivable that alterations of connexin 26 expression could contribute to the multifactorial disease process in cholesteatoma by modifying the cell-to-cell communication that is important in proliferation and migration of keratinocytes.