Micro RNAs and Circular RNAs in Different Forms of Otitis Media.

The aim of this comprehensive review was to present the current knowledge on the role of microRNAs (miRNAs) in acute, recurrent, and chronic forms of otitis media. Special attention was focused on cholesteatoma of the middle ear. MicroRNAs modulate gene expression, which, in turn, influences the development and likelihood of the recurrence of acute and aggressive chronic middle ear inflammatory processes. Moreover, this study discusses the modulating role of a specific subgroup of noncoding RNA, circular RNA (circRNA). Recognizing the precise potential pathways and the mechanisms of their function may contribute to a better understanding of the molecular bases of middle ear diseases and identifying novel methods for treating this demanding pathology. Articles published between 2009 and 2022 were used in this analysis. In this review, we provide a complete overview of the latest progress in identifying the role and mechanisms of particular miRNAs and circRNAs in acute, recurrent and chronic forms of otitis media.

Review of potential medical treatments for middle ear cholesteatoma.

Middle ear cholesteatoma (MEC), is a destructive, and locally invasive lesion in the middle ear driven by inflammation with an annual incidence of 10 per 100,000. Surgical extraction/excision remains the only treatment strategy available and recurrence is high (up to 40%), therefore developing the first pharmaceutical treatments for MEC is desperately required. This review was targeted at connecting the dysregulated inflammatory network of MEC to pathogenesis and identification of pharmaceutical targets. We summarized the numerous basic research endeavors undertaken over the last 30+ years to identify the key targets in the dysregulated inflammatory pathways and judged the level of evidence for a given target if it was generated by in vitro, in vivo or clinical experiments. MEC pathogenesis was found to be connected to cytokines characteristic for Th1, Th17 and M1 cells. In addition, we found that the inflammation created damage associated molecular patterns (DAMPs), which further promoted inflammation. Similar positive feedback loops have already been described for other Th1/Th17 driven inflammatory diseases (arthritis, Crohn's disease or multiple sclerosis). A wide-ranging search for molecular targeted therapies (MTT) led to the discovery of over a hundred clinically approved drugs already applied in precision medicine. Based on exclusion criteria designed to enable fast translation as well as efficacy, we condensed the numerous MTTs down to 13 top drugs. The review should serve as groundwork for the primary goal, which is to provide potential pharmaceutical therapies to MEC patients for the first time in history. Video Abstract.

Middle ear cholesteatoma (MEC) is a destructive and locally invasive ulcerated lesion in the middle ear driven by inflammation which occurs in 10 out of 100,000 people annually. Surgical extraction/excision is the only treatment strategy available and recurrence is high (up to 40% after ten years), therefore developing the first pharmaceutical treatments for MEC is desperately required. This review is focused on the connections between inflammation and MEC pathogenesis. These connections can be used as attack points for pharmaceuticals. For this we summarized the results of research undertaken over the last 30 + years. MEC pathogenesis can be described by specific inflammatory dysregulation already known from arthritis, Crohn's disease or multiple sclerosis. A hallmark of this dysregulation are positive feedback loops of the inflammation further amplifying itself in a vicious circle-like manner. We have identified over one hundred drugs which are already used in clinic to treat other inflammatory diseases, and could potentially be repurposed to treat MEC. To improve and expedite clinical success rates, we applied certain criteria based on our literature searches and condensed these drugs down to the 13 top drugs. We hope the review will serve as groundwork for the primary goal, which is to provide potential pharmaceutical therapies to MEC patients for the first time in history.

Single-Cell Transcriptome Profiling Identifies Phagocytosis-Related Dual-Feature Cells in A Model of Acute Otitis Media in Rats.

Background: The molecular mechanisms of acute otitis media (AOM) development, and the intercellular crosstalk within the multicellular ecosystem of AOM, are not clear. Methods: We established a model of AOM in rats (with normal rats as controls) and undertook single-cell RNA sequencing (scRNA-seq) for the middle-ear mucosa (MEM). Cell clustering and trajectory analyses were undertaken using Seurat and Monocle 2 packages in R software. Pathway analyses were done by gene set enrichment analysis (GSEA). Cell-cell interactions were inferred by CellChat. Cell scores were calculated to identify cells with dual-feature. Results: A total of 7023 cells from three samples of inflamed MEM and 5258 cells from three samples of healthy MEM underwent scRNA-seq, which identified 20 cell clusters belonging to eight major cell types. After exposure to lipopolysaccharide, the MEM underwent significant conversion of cell types characterized by rapid infiltration of macrophages and neutrophils. M2 macrophages seemed to play a key part in inflammatory intercellular crosstalk, which facilitated the maintenance and proliferation of macrophages, cell chemotaxis, and regulation of the proinflammatory activities of cytokines. Three rare cell clusters with phagocytosis-related dual-feature were also identified. They coexisted with professional phagocytes in the MEM, and displayed distinct immunoregulatory functions by maintaining a normal immune microenvironment or influencing inflammation progression. Conclusions: Macrophages might be the "master" initiators and regulators of the inflammatory response of the MEM to external stimuli. And their functions are fulfilled by a specific polarization status (M2) and sophisticated intercellular crosstalk via certain signaling pathways. Besides, the coexistence of professional phagocytes and non-professional phagocytes as well as their interplay in the MEM provides new clues for deciphering the underlying pathogenic mechanisms of AOM.

Glycolytic Metabolism Is Critical for the Innate Antibacterial Defense in Acute Streptococcus pneumoniae Otitis Media.

Objective: Streptococcus pneumoniae (S.pn) is a common respiratory pathogen and a frequent cause of acute otitis media (AOM) in children. However, little is known about the immunometabolism during AOM. This study was to assess the presence of glucose metabolic reprogramming during AOM and its underlying mechanism affecting inflammatory response and middle ear injury. Methods: The levels of glycolytic metabolism were evaluated by measuring the expression of glycolysis-related genes and the production of metabolites. HE stain, immunofluorescence, immunohistochemistry, enzyme-linked immunosorbent assay (ELISA) and Western blot were performed to measure the effect of glucose metabolic reprogramming on inflammatory response, pneumococcal clearance, hypoxia-inducible factor 1 alpha (HIF-1α) expression and cytokine secretion during AOM, respectively. Results: The analysis of microarray revealed an increase of the expression of glycolysis-related genes during S.pn-induced AOM, which was verified by real-time PCR. Increased glycolysis promoted the production of IL-1ß and TNF-α and facilitated the clearance of S.pn by enhancing phagocytosis and killing capability of neutrophils, but also aggravated the middle ear injury. Furthermore, these pathogenic effects could be reversed after glycolytic inhibitor 2DG treatment. Additionally, HIF-1α was observed to involve in glycolytic metabolism during AOM. Conclusion: S.pn infection induced increased glycolysis conversion during AOM, which promoted inflammatory responses and bacterial clearance, but also aggravated tissue damage.

Middle Ear "Adenoma": a Neuroendocrine Tumor with Predominant L Cell Differentiation.

This morphological and immunohistochemical study demonstrates that tumors currently known as "middle ear adenomas" are truly well-differentiated epithelial neuroendocrine tumors (NETs) composed of cells comparable to normal intestinal L cells, and therefore, these tumors resemble hindgut NETs. These tumors show consistent expression of glucagon, pancreatic polypeptide, PYY, and the transcription factor SATB2, as well as generic neuroendocrine markers and keratins. The same L cell markers are expressed by cells within the normal middle ear epithelium. These markers define a valuable immunohistochemical profile that can be used for differential diagnosis of middle ear neoplasms, particularly in distinguishing epithelial NETs from paragangliomas. The discovery of neuroendocrine cells expressing the same markers in non-neoplastic middle ear mucosa opens new areas of investigation into the physiology of the normal middle ear and the pathophysiology of middle ear disorders.

The transcriptional landscape of the cultured murine middle ear epithelium in vitro.

Otitis media (OM) is the most common paediatric disease and leads to significant morbidity. Although understanding of underlying disease mechanisms is hampered by complex pathophysiology, it is clear that epithelial abnormalities underpin the disease. The mechanisms underpinning epithelial remodelling in OM remain unclear. We recently described a novel in vitro model of mouse middle ear epithelial cells (mMEECs) that undergoes mucociliary differentiation into the varied epithelial cell populations seen in the middle ear cavity. We now describe genome wide gene expression profiles of mMEECs as they undergo differentiation. We compared the gene expression profiles of original (uncultured) middle ear cells, confluent cultures of undifferentiated cells and cells that had been differentiated for 7 days at an air liquid interface (ALI). >5000 genes were differentially expressed among the three groups of cells. Approximately 4000 genes were differentially expressed between the original cells and day 0 of ALI culture. The original cell population was shown to contain a mix of cell types, including contaminating inflammatory cells that were lost on culture. Approximately 500 genes were upregulated during ALI induced differentiation. These included some secretory genes and some enzymes but most were associated with the process of ciliogenesis. The data suggest that the in vitro model of differentiated murine middle ear epithelium exhibits a transcriptional profile consistent with the mucociliary epithelium seen within the middle ear. Knowledge of the transcriptional landscape of this epithelium will provide a basis for understanding the phenotypic changes seen in murine models of OM.

Suppression of lncRNA MALAT1 Reduces LPS- or IL-17A-Induced Inflammatory Response in Human Middle Ear Epithelial Cells via the NF-κB Signaling Pathway.

Otitis media (OM) is a common inflammatory disease of the middle ear cavity and mainly occurs in children. As a critical regulator of inflammation response, the nuclear factor kappa B (NF-κB) pathway has been found to play an essential role in the pathogenesis of various human diseases. The aim of this study was to explore the potential mechanism under the inflammatory response of human middle ear epithelial cells (HMEECs). We established in vitro models of OM by treating HMEECs with lipopolysaccharide (LPS) or interleukin 17A (IL-17A). Enzyme-linked immunosorbent assay and western blot analysis were used to measure the inflammatory response of HMEECs under LPS or IL-17A stimulation. The results revealed that the concentrations of proinflammatory cytokines (p < 0.001) and protein levels of mucin (MUC) (for MUC5AC, p = 0.002, p = 0.004; for MUC8, p = 0.004, p < 0.001) were significantly elevated by LPS or IL-17A stimulation in HMEECs. Moreover, we found that LPS or IL-17A treatment promoted the phosphorylation of IκBα (for p-IκBα, p = 0.018, p = 0.002; for IκBα, p = 0.238, p = 0.057) and the translocation of p65 from cytoplasm to nucleus in HMEECs (for nucleus p65, p = 0.01; for cytoplasm p65, p < 0.001). In addition, RT-qPCR analysis revealed that long noncoding RNA (lncRNA) metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) was verified to be upregulated in LPS- or IL-17A-stimulated HMEECs (p < 0.001). Western blot analysis and immunofluorescence staining assay revealed that that MALAT1 knockdown significantly suppressed the activation of the NF-κB pathway by reducing phosphorylated IκBα levels and inhibiting the nuclear translocation of p65 (p < 0.001) in LPS- or IL-17A-stimulated HMEECs (for p-IκBα, p < 0.001; for IκBα, p = 0.242, p = 0.647). Silence of MALAT1 decreased the proinflammatory cytokine production and MUC protein levels (p < 0.001). Furthermore, rescue assays revealed that the increase of proinflammatory cytokine production (for TNF-α, p = 0.002, p = 0.015; for IL-1ß, p < 0.001, p = 0.006; for IL-6, p = 0.002, p < 0.001) and MUC protein levels (for MUC5AC, p = 0.001, p < 0.001; for MUC8, p < 0.001, p = 0.001) induced by MALAT1 overexpression was neutralized by 4-N-[2-(4-phenoxyphenyl) ethyl] quinazoline-4, 6-diamine (QNZ) treatment in LPS- or IL-17A-stimulated HMEECs. In conclusion, MALAT1 promotes inflammatory response in LPS- or IL-17A- stimulated HMEECs via the NF-κB signaling pathway, which may provide a potential novel insight for the treatment of OM.

The Possible Role of Sclerostin in the Pathogenesis of Tympanosclerosis.

OBJECTIVE: The aim of this study was to investigate sclerostin (SOST) expression in a rat model of experimental tympanosclerosis (TS) and its possible role in the formation of TS. MATERIALS AND METHODS: Thirty-four SD rats were randomly divided into 2 groups: experimental group (n = 17) and normal group (n = 17). The left tympanic cavities in the experimental group were inoculated with methicillin-resistant Staphylococcus aureus. The changes of tympanic membranes were examined and recorded under otoendoscope. Haematoxylin-eosin staining was adopted to detect the morphological changes in the tympanic membrane and middle ear mucosa. Immunohistochemistry and Western blot analysis were used to observe the expression of SOST, Wnt3a, ß-catenin, and P-ERK1/2. RESULTS: In the experimental group, sclerotic lesions were observed in 54.5% ears in the end of 6 weeks. Morphological changes such as mucosa incrassation, inflammatory cells infiltration, fibrous tissue proliferation, and interstitial tissue incrassation prominently appeared in the tympanic membrane and middle ear mucosa. SOST protein was mainly distributed in the cytoplasm of epithelial cells and gland cells, the expression of which increased significantly in the calcified experimental ears. In addition, expression levels of Wnt3a, ß-catenin, and P-ERK1/2 increased significantly in the calcified group too. CONCLUSION: The upregulated expression level of SOST may be involved in the formation of TS, first, through the pro-phosphorylation of ERK1/2 in the inflammatory stage, and then through the enhancement of Wnt3a in the osteogenic stage.

miR-210 regulates the inflammation of otitis media with effusion by inhibiting the expression of hypoxia-inducible factor (HIF)-1a.

Otitis media with effusion (OME) is the major cause of hearing impairment in children. miR-210 plays a critical role in inflammatory diseases, however, its role in OME is unknown. In this study, the miR-210 level in serum and middle ear effusion of is significantly down-regulated in serum, middle ear effusion from OME patients (100 cases) compared with healthy volunteers (50 cases). The expression of miR-210 is closely related to inflammatory factors and bone conduction disorder in patients with OME. In the in vitro study，the miR-210 level is significantly reduced in culture supernatant of lipopolysaccharide (LPS) treated human middle ear epithelial cells (HMEECs). miR-210 overexpression inhibited the LPS-induced in inflammatory cytokines production, cell viability reduction and cell apoptosis. Bioinformatics and dual-luciferase reporter assay showed that HIF-1a was a target gene of miR-210. The biological effects of miR-210 on cell viability, cell apoptosis and inflammation cytokines in LPS-induced HMEECs were reversed by HIF-1a overexpression. Furthermore, phosphorylation of NF-κB p65 was significantly decreased by miR-210 mediated HIF-1a in LPS-induced HMEECs. This study suggested that miR-210 may play a role in OME. Further studies are warranted to assess miR-210 as a potential target for the diagnosis and treatment of OME.

Social buffering of cortisol release and tympanic temperature asymmetries during novelty and isolation stress in marmoset monkeys.

Novel environments induce a conflicting emotional approach-withdrawal state that triggers stress-related reactions. Social support through the presence of a highly familiar conspecific buffers the individual against such challenges. Although aversive events seem to be predominantly processed by the right hemisphere, this is still under debate and little is known about functional cerebral asymmetries in nonhuman primates during novelty stress, isolation and social buffering. Here we isolated adult marmoset monkeys in a new open-field arena or in their familiar home-cages to establish hemisphere activity and whether the pairmate's presence buffers the response. Monkeys socially isolated in either location had higher circulating cortisol levels than non-isolated marmosets, but different hemisphere activity patterns indicated by changes in baseline tympanic membrane temperatures (TMT). The bilateral increase in the monkeys that were isolated in the unfamiliar location may reflect an approach-withdrawal conflict. The left-sided increase in the home-cage isolation group was negatively related to cortisol release, this being potentially associated with a more proactive/approach-prone temperament. Interestingly, TMT and cortisol were unaltered when the pairmate was present. Thus, positive social interaction reduces the perceived intensity of the threat, alters hemisphere asymmetries and blocks the hormonal response to novelty stress, consistent with a buffering effect.

Transcriptomic analysis of tobacco-flavored E-cigarette and menthol-flavored E-cigarette exposure in the human middle ear.

Electronic cigarettes (e-cigarettes) are the most widely used electronic nicotine delivery systems and are designed to imitate smoking and aid in smoking cessation. Although the number of e-cigarette users is increasing rapidly, especially among young adults and adolescents, the potential health impacts and biologic effects of e-cigarettes still need to be elucidated. Our previous study demonstrated the cytotoxic effects of electronic liquids (e-liquids) in a human middle ear epithelial cell (HMEEC-1) line, which were affected by the manufacturer and flavoring agents regardless of the presence of nicotine. In this study, we aimed to evaluate the gene expression profile and identify potential molecular modulator genes and pathways in HMEEC-1 exposed to two different e-liquids (tobacco- and menthol-flavored). HMEEC-1 was exposed to e-liquids, and RNA sequencing, functional analysis, and pathway analysis were conducted to identify the resultant transcriptomic changes. A total of 843 genes were differentially expressed following exposure to the tobacco-flavored e-liquid, among which 262 genes were upregulated and 581 were downregulated. Upon exposure to the menthol-flavored e-liquid, a total of 589 genes were differentially expressed, among which 228 genes were upregulated and 361 were downregulated. Among the signaling pathways associated with the differentially expressed genes mediated by tobacco-flavored e-liquid exposure, several key molecular genes were identified, including IL6 (interleukin 6), PTGS2 (prostaglandin-endoperoxide synthase 2), CXCL8 (C-X-C motif chemokine ligand 8), JUN (Jun proto-oncogene), FOS (Fos proto-oncogene), and TP53 (tumor protein 53). Under menthol-flavored e-liquid treatment, MMP9 (matrix metallopeptidase 9), PTGS2 (prostaglandin-endoperoxide synthase 2), MYC (MYC proto-oncogene, bHLH transcription factor), HMOX1 (heme oxygenase 1), NOS3 (nitric oxide synthase 3), and CAV1 (caveolin 1) were predicted as key genes. In addition, we identified related cellular processes, including inflammatory responses, oxidative stress and carcinogenesis, under exposure to tobacco- and menthol-flavored e-liquids. We identified differentially expressed genes and related cellular processes and gene signaling pathways after e-cigarette exposure in human middle ear cells. These findings may provide useful evidence for understanding the effect of e-cigarette exposure.

Uncovering the secreted signals and transcription factors regulating the development of mammalian middle ear ossicles.

The mammalian middle ear comprises a chain of ossicles, the malleus, incus, and stapes that act as an impedance matching device during the transmission of sound from the tympanic membrane to the inner ear. These ossicles are derived from cranial neural crest cells that undergo endochondral ossification and subsequently differentiate into their final functional forms. Defects that occur during middle ear development can result in conductive hearing loss. In this review, we summarize studies describing the crucial roles played by signaling molecules such as sonic hedgehog, bone morphogenetic proteins, fibroblast growth factors, notch ligands, and chemokines during the differentiation of neural crest into the middle ear ossicles. In addition to these cell-extrinsic signals, we also discuss studies on the function of transcription factor genes such as Foxi3, Tbx1, Bapx1, Pou3f4, and Gsc in regulating the development and morphology of the middle ear ossicles.

Multi-omic studies on missense PLG variants in families with otitis media.

Otitis media (OM), a very common disease in young children, can result in hearing loss. In order to potentially replicate previously reported associations between OM and PLG, exome and Sanger sequencing, RNA-sequencing of saliva and middle ear samples, 16S rRNA sequencing, molecular modeling, and statistical analyses including transmission disequilibrium tests (TDT) were performed in a multi-ethnic cohort of 718 families and simplex cases with OM. We identified four rare PLG variants c.112A > G (p.Lys38Glu), c.782G > A (p.Arg261His), c.1481C > T (p.Ala494Val) and c.2045 T > A (p.Ile682Asn), and one common variant c.1414G > A (p.Asp472Asn). However TDT analyses for these PLG variants did not demonstrate association with OM in 314 families. Additionally PLG expression is very low or absent in normal or diseased middle ear in mouse and human, and salivary expression and microbial α-diversity were non-significant in c.1414G > A (p.Asp472Asn) carriers. Based on molecular modeling, the novel rare variants particularly c.782G > A (p.Arg261His) and c.2045 T > A (p.Ile682Asn) were predicted to affect protein structure. Exploration of other potential disease mechanisms will help elucidate how PLG contributes to OM susceptibility in humans. Our results underline the importance of following up findings from genome-wide association through replication studies, preferably using multi-omic datasets.

Periostin in middle ear mucosa according to eosinophilic otitis media severity: Middle ear pathology-based treatment.

OBJECTIVE: Eosinophilic otitis media (EOM) is an intractable disorder associated with bronchial asthma and chronic rhinosinusitis with nasal polyposis. Periostin is an extracellular matrix protein secreted by fibroblasts in response to interleukin (IL)-4 and/or IL-13 and is a known marker for eosinophilic disorders. We assessed serum periostin levels and expression of periostin in the middle ear mucosa according to three grade of EOM severity (grade1 to 3). METHODS: 68 patients of blood and serum samples were corrected by whom diagnose bilateral EOM in Jichi Medical University Saitama Medical Center from January 2015 to June 2017.Immunohistochemical evaluation was performed to 18 EOM middle ears mucosa samples, which cauterized in tree groups and compared to that of chronic otitis media (COM). RESULTS: Serum periostin levels was significantly higher in EOM patients than in COM patients (EOM, 125.0 ± 45.5 ng/mL; COM, 79.4 ± 38.3 ng/mL; P<0.0001). The expression of periostin immunopositivity in the EOM middle ear mucosa was significantly greater in severe cases (grade3 samples) than others (grade1 and grade2 samples) (P <0.001 and P = 0.011, respectively). Periostin was expressed at the lamina propria especially in severe EOM cases and the cases had little response to glucocorticoids treatment. CONCLUSION: This study showed that periostin in the middle ear mucosa was correlated with EOM severity, and EOM with highly expressed periostin had difficulty in glucocorticoids treatment.

Panel 2- recent advance in otitis media bioinformatics.

OBJECTIVES: To update the medical literature on recent large-scale studies employing bioinformatics data analysis tools in otitis media (OM) disease models with a principal focus on developments in the past 5 years. DATA SOURCES: Pubmed indexed peer-reviewed articles. REVIEW METHODS: Comprehensive review of the literature using the following search terms: 'genomics, inflammasome, microRNA, proteomics, transcriptome, bioinformatics' with the term 'otitis media', and 'middle ear'. Included articles published in the English language from January 1, 2015-April 1, 2019. IMPLICATIONS FOR PRACTICE: Large scale bioinformatics tools over the past five years lend credence to the paradigm of innate immune response playing a critical role in host defense against bacteria contributing to Otitis Media (OM) progression from acute to chronic. In total, genomic, miRNAomic, and proteomic analyses all point to the need for a tightly regulated innate immune and inflammatory response in the middle ear. Currently, there is an urgent need for developing novel therapeutic strategies to control immunopathology and tissue damage, improve hearing and enhance host defense for both acute and chronic OM based on full understanding of the basic molecular pathogenesis of OM.

Keratinocyte growth factor (KGF) induces stem/progenitor cell growth in middle ear mucosa.

OBJECTIVE: The middle ear epithelium is derived from the neural crest and endoderm, which line distinct regions of the middle ear cavity. In this study, we investigated the localization of stem/progenitor cells in the middle ear mucosa of adult mice and the effects of keratinocyte growth factor (KGF) on the cell kinetics of stem/progenitor cells in vivo. METHODS: In this study, after KGF-expression vector was transfected in the ear, two kinds of thymidine analogues, BrdU and EdU, were transferred at different time points. BrdU was detected by immunohistochemistry and EdU was detected by click chemistry. We also performed immunohistochemistry using anti-Keratin14 (K14) antibody (an undifferentiated epithelial cell marker), anti-p63 antibody (a stem/progenitor cell marker) and anti-acetylated α-tubulin antibody (a ciliated epithelial cell marker). RESULTS: A large number of EdU-positive cells were detected in the thickened mucosal epithelium of the pars flaccida and attic region at Day 1 after KGF transfection. Interestingly, in the mucosal epithelium overlying the promontory of the cochlea, many EdU-positive cells were detected. These cells were also positive for K14 and p63. The acetylated α-tubulin positive cells were reduced in the attic region at Day 1 after KGF transfection. CONCLUSION: These findings indicate that KGF over-expression may increase stem/progenitor cell proliferation in the mucosal epithelium not only within the attic which is typical in middle ear cholesteatoma, but also overlying the promontory of the cochlea.

[The research progress of keratin's roles in the pathology of middle ear cholesteatoma].

Keratin (K) is the main component of the epithelial cell mesenchymal cytoskeleton, which protects the integrity of epithelial cells and maintains the function of normal epithelial cells. The expression of keratin affects epidermal proliferation and differentiation, and so as to be used as a marker for proliferation, differentiation and migration of keratinocytes. Middle ear cholesteatoma is one of the common ear diseases. In the middle ear cholesteatoma, keratinocytes over-proliferate and keratin debris accumulates. In this paper, we reviewed the recent studies on middle ear cholesteatoma and explained the possible mechanisms of keratin in the pathogenesis of middle ear cholesteatoma from the aspects of "proliferation" and " bone resorption ". At the same time, the existing problems as well as the prospect of the future research were discussed.

The CaV1.2 L-type calcium channel regulates bone homeostasis in the middle and inner ear.

Bone remodeling of the auditory ossicles and the otic capsule is highly restricted and tightly controlled by the osteoprotegerin (OPG)/receptor activator of nuclear factor kappa-Β ligand (RANKL)/receptor activator of nuclear factor kappa-Β (RANK) system. In these bony structures, a pathological decrease in OPG expression stimulates osteoclast differentiation and excessive resorption followed by accrual of sclerotic bone, ultimately resulting in the development of otosclerosis, a leading cause of deafness in adults. Understanding the signaling pathways involved in maintaining OPG expression in the ear would shed light on the pathophysiology of otosclerosis and other ear bone-related diseases. We and others previously demonstrated that Ca2+ signaling through the L-type CaV1.2 Ca2+ channel positively regulates OPG expression and secretion in long bone osteoblasts and their precursor cells in vitro and in vivo. Whether CaV1.2 regulates OPG expression in ear bones has not been investigated. We drove expression of a gain-of-function CaV1.2 mutant channel (CaV1.2TS) using Col2a1-Cre, which we found to target osteochondral/osteoblast progenitors in the auditory ossicles and the otic capsule. Col2a1-Cre;CaV1.2TS mice displayed osteopetrosis of these bones shown by µCT 3D reconstruction, histological analysis, and lack of bone sculpting, findings similar to phenotypes seen in mice with an osteoclast defect. Consistent with those observations, we found that Col2a1-Cre;CaV1.2TS mutant mice showed reduced osteoclasts in the otic capsule, upregulated mRNA expression of Opg and Opg/Rankl ratio, and increased mRNA expression of osteoblast differentiation marker genes in the otic capsule, suggesting both an anti-catabolic and anabolic effect of CaV1.2TS mutant channel contributed to the observed morphological changes of the ear bones. Further, we found that Col2a1-Cre;CaV1.2TS mice experienced hearing loss and displayed defects of body balance in behavior tests, confirming that the CaV1.2-dependent Ca2+ influx affects bone structure in the ear and consequent hearing and vestibular functions. Together, these data support our hypothesis that Ca2+ influx through CaV1.2TS promotes OPG expression from osteoblasts, thereby affecting bone modeling/remodeling in the auditory ossicles and the otic capsule. These data provide insight into potential pathological mechanisms underlying perturbed OPG expression and otosclerosis.

Role of ectodysplasin signalling in middle ear and nasal pathology in rat and mouse models of hypohidrotic ectodermal dysplasia.

Patients with mutations in the ectodysplasin receptor signalling pathway genes - the X-linked ligand ectodysplasin-A (EDA), the receptor EDAR or the receptor adapter EDARADD - have hypohidrotic ectodermal dysplasia (HED). In addition to having impaired development of teeth, hair, eccrine sweat glands, and salivary and mammary glands, HED patients have ear, nose and throat disease. The mouse strains Tabby (EdaTa ) and downless (Edardl-J/dl-J ) have rhinitis and otitis media due to loss of submucosal glands in the upper airway. We report that prenatal correction of EDAR signalling in EdaTa mice with the agonist anti-EDAR antibody rescues the auditory-tube submucosal glands and prevents otitis media, rhinitis and nasopharyngitis. The sparse- and wavy-haired (swh) rat strain carries a mutation in the Edaradd gene and has similar cutaneous HED phenotypes to mouse models. We report that auditory-tube submucosal glands are smaller in the homozygous mutant Edaraddswh/swh than those in unaffected heterozygous Edaraddswh/+ rats, and that this predisposes them to otitis media. Furthermore, the pathogenesis of otitis media in the rat HED model differs from that in mice, as otitis media is the primary pathology, and rhinitis is a later-onset phenotype. These findings in rodent HED models imply that hypomorphic as well as null mutations in EDAR signalling pathway genes may predispose to otitis media in humans. In addition, this work suggests that the recent successful prenatal treatment of X-linked HED (XLHED) in humans may also prevent ear, nose and throat disease, and provides diagnostic criteria that distinguish HED-associated otitis media from chronic otitis media with effusion, which is common in children.