Expression of RANKL and OPG in Middle Ear Cholesteatoma Tissue

Effect of Tacrolimus on Development of Experimental Cholesteatoma

PURPOSE

Cholesteatoma is a benign yet aggressive middle ear tumor characterized by keratin accumulation and chronic inflammation, leading to bone resorption and severe complications. This study aimed to investigate the effects of Tacrolimus, a potent immunosuppressive agent, on cholesteatoma formation in a propylene glycol (PG)-induced experimental model.

METHODS

Fifteen male Wistar Albino rats were used, with right ears serving as controls and left ears as the experimental group. Cholesteatoma was induced by injecting 60 % PG combined with Gentamicin and Saline into the middle ear. The experimental group received the same solution supplemented with Tacrolimus. Histological evaluation included keratinization, inflammation, fibrosis, and vascular proliferation. Statistical analysis was performed to compare the control and experimental groups.

RESULTS

Experimental cholesteatoma formation was achieved in 80 % of ears injected with PG (12 out of 15 ears). In the Tacrolimus-treated group, cholesteatoma formation was observed in only 1 ear (6.7 %), while the remaining 14 ears showed no evidence of keratin lamellae (p < 0.05). Although Tacrolimus significantly inhibited epithelial keratinization and invagination, no significant differences were found between groups regarding acute or chronic inflammation, fibrosis, or vascular proliferation (p > 0.05).

CONCLUSION

Tacrolimus demonstrated a strong inhibitory effect on cholesteatoma formation in this experimental model by markedly reducing epithelial keratinization and invagination. These findings suggest Tacrolimus's potential as a novel therapeutic agent for cholesteatoma. However, further studies are required to assess its safety, long-term efficacy, and clinical applicability.

The Science of Cholesteatoma

Cholesteatoma is a potential end-stage outcome of chronic ear infections that can result in the destruction of temporal bone structures with potential resultant hearing loss, vertigo, and intracranial infectious complications. There is currently no treatment apart from surgery for this condition, and despite years of study, the histopathogenesis of this disease remains poorly understood. This review is intended to summarize our accumulated knowledge of the mechanisms of cholesteatoma development and the underlying molecular biology. Attention will be directed particularly to recent developments, covering many potential pharmacologic targets that could be used to treat this disease in the future.

Comparison of Post-auricular Soft Tissue and Post-auricular Soft Tissue With Autologous Bone Pate in Obliteration of the Canal Wall Down Mastoidectomy Cavity

Background The surgical management of chronic otitis media (COM) with squamous disease is canal wall down mastoidectomy (CWDM). Canal wall down procedures require the obliteration of the newly formed cavity to mitigate complications. Soft tissue flaps, including Rambo flap, Hong Kong flap, Palva flap, and inferior-based fascio-periosteal flap, as well as autologous bone pâté, have been the most successful and commonly used materials for obliteration over the past two decades. Although each flap has its advantages, the Palva flap is considered superior, primarily because of its ease of use and the simplicity of its design. In this study, we intend to evaluate the effectiveness of mastoid obliteration using autologous bone pate with Palva flap compared to Palva flap (post-auricular fibro-periosteal soft tissue) in patients who underwent CWDM. Methods Sixty-two patients with COM with squamous disease were included in the study. The patients underwent CWDM with tympanoplasty and meatoplasty, followed by cavity obliteration using two different methods: group A - obliteration with Palva flap (post-auricular fibro-periosteal soft tissue) and group B - obliteration with Palva flap and bone pate. The patients were evaluated for cavity problems on post-operative days 21, 30, 60, 90, and 180, based on a 10-point scale compiled from the literature. Results Our study found that the majority of patients had right-sided disease and were between 41 and 60 years of age. Five out of sixty-two (8.1%) patients developed cavity problems, three in group A (9.7%) and two in group B (6.5%). The incidence of cavity problems was almost the same in both groups. The cavity problems were as follows: vertigo (1/62, 1.6%), surgical site infection (2/62, 3.2%), and graft failure (2/62, 3.2%). However, there were no statistically significant differences (p-value: 0.62) between either of the obliteration methods in terms of mitigating cavity problems. Conclusion Post-auricular soft tissue and post-auricular soft tissue with autologous bone pate in the obliteration of the CWDM cavity provided similar results in terms of mitigating cavity problems.

Cholesteatoma Severely Impacts the Integrity and Bone Material Quality of the Incus

Cholesteatoma can lead to progressive destruction of the auditory ossicles along with conductive hearing loss but precise data on the microstructural, cellular, and compositional aspects of affected ossicles are not available. Here, we obtained incus specimens from patients who had cholesteatoma with conductive hearing loss. Incudes were evaluated by micro-computed tomography, histomorphometry on undecalcified sections, quantitative backscattered electron imaging, and nanoindentation. Results were compared with two control groups taken from patients with chronic otitis media as well as from skeletally intact donors at autopsy. The porosity of incus specimens was higher in cholesteatoma than in chronic otitis media, along with a higher osteoclast surface per bone surface. Histomorphometric assessment revealed higher osteoid levels and osteocyte numbers in cholesteatoma incudes. Incudes affected by cholesteatoma also showed lower matrix mineralization compared with specimens from healthy controls and chronic otitis media. Furthermore, the modulus-to-hardness ratio was higher in cholesteatoma specimens compared with controls. Taken together, we demonstrated increased porosity along with increased osteoclast indices, impaired matrix mineralization, and altered biomechanical properties as distinct features of the incus in cholesteatoma. Based on our findings, a possible impact of impaired bone quality on conductive hearing loss should be further explored.

Bone destruction in chronic otitis media is not mediated by the RANKL pathway or estrogen receptor-alpha

BACKGROUND

Chronic otitis media with or without cholesteatoma progresses with various degrees of bone resorption and remodeling. Estrogen mediates osteoprotective effects through the receptor activator of NF-κB ligand (RANKL) pathway, which is mainly mediated by estrogen receptor-alpha (ER-α).

OBJECTIVES

The present study investigated the expression patterns of receptor activator of NF-κB (RANK), osteoprotegerin (OPG), RANKL, and ER-α in pathological tissue from patients with chronic otitis media to determine the roles of those factors in osteolytic mechanisms underlying the pathogenesis of chronic otitis media.

METHODS

Normal and pathological specimens from 18 patients with chronic otitis media were examined.

RESULTS

There were no significant differences in RANK, OPG, RANKL, or ER-α mRNA expression between normal and pathological specimens of epithelial tissue.

CONCLUSIONS

Our findings suggested that RANK, OPG, RANKL, and ER-α are not associated with the bone destruction in chronic otitis media; other cytokines may directly activate the osteoclasts in chronic 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.

Bacterial and Fungal Infections Promote the Bone Erosion Progression in Acquired Cholesteatoma Revealed by Metagenomic Next-Generation Sequencing

An acquired cholesteatoma generally occurs as a consequence of otitis media and eustachian tube dysfunction. Patients with acquired cholesteatoma generally present with chronic otorrhea and progressive conductive hearing loss. There are many microbes reportedly associated with acquired cholesteatoma. However, conventional culture-based techniques show a typically low detection rate for various pathogenetic bacteria and fungi. Metagenomic next-generation sequencing (mNGS), an emerging powerful platform offering higher sensitivity and higher throughput for evaluating many samples at once, remains to be studied in acquired cholesteatoma. In this study, 16 consecutive patients from January 2020 to January 2021 at the Second Affiliated Hospital of Zhejiang University School of Medicine (SAHZU) were reviewed. We detected a total of 31 microbial species in patients, mNGS provided a higher detection rate compared to culture (100% vs. 31.25%, p = 0.000034). As the severity of the patient's pathological condition worsens, the more complex types of microbes were identified. The most commonly detected microbial genus was Aspergillus (9/16, 56.25%), especially in patients suffering from severe bone erosion. In summary, mNGS improves the sensibility to identify pathogens of cholesteatoma patients, and Aspergillus infections increase bone destruction in acquired cholesteatoma.

Osteoclastic activity in chronic otitis media with cholesteatoma-related bone destruction

BACKGROUND

Cholesteatoma-related bone destruction is the cause of many complications due to chronic otitis media. This study aimed to evaluate osteoclastic activity in cholesteatoma-related bone destruction using tartrate-resistant acid phosphatase 5b, an enzyme specific to osteoclastic activity.

METHOD

Seventy-two patients diagnosed with chronic otitis media were included in this study and were divided into two groups: with and without bone destruction. The blood serum and tissue tartrate-resistant acid phosphatase 5b levels from both groups were compared.

RESULTS

There were no significant differences in the level of serum enzymes between both groups. However, in tissue samples, tartrate-resistant acid phosphatase 5b levels were significantly lower in the bone destruction group than the group without bone destruction.

CONCLUSION

This study determined that the level of tartrate-resistant acid phosphatase 5b, a specific enzyme for osteoclastic activity in cholesteatoma-related bone destruction, is locally decreased. This data suggests that osteoclastic activity may decrease in cholesteatoma-related bone destruction. However, further experimental and clinical studies are required to clarify this highly complex mechanism.

Patterns of Bone Damage in Patients With Chronic Middle Ear Inflammation

BACKGROUND

Despite different etiologies, chronic otitis media involves the damaging and restructuring of bone tissue. The inflammatory process destroys elements of the ossicular chain, and bone lesions may appear that allow the development of otogenous complications.

AIMS/OBJECTIVES

A correlation between the degree of damage to the ossicular chain as well as the bony walls of the middle ear and the type of chronic inflammatory lesions was sought. Destructive changes to bones were observed using scanning microscopy.

MATERIAL AND METHODS

The removed damaged fragments of the ossicles were prepared for evaluation with a scanning microscope. Preparations were sputter-coated with a thin layer of gold and subsequently evaluated.

RESULTS

Of 220 surgeries carried out in the discussed period, destruction of the middle ear bone walls, opening the way for the development of intracranial complications, was found in 27 patients. Most of them had ongoing chronic otitis media with granulation.

CONCLUSIONS

(1) Bone loss of the skull base was observed more frequently in patients with chronic otitis media with granulation than with cholesteatoma. (2) In chronic otitis media with cholesteatoma, damage to the ossicular chain was observed significantly more frequently than in the case of otitis media with granulation.

Expression of PTHrP and RANKL in acquired middle ear cholesteatoma epithelium

Background: Regarded as the most important clinical characteristic of middle ear cholesteatoma, the exact mechanism of bone resorption in cholesteatoma still remains unknown.Objectives: To investigate protein expression of PTHrP and RANKL in acquired middle ear cholesteatoma epithelium and analyze their functional roles in the etiopathogenesis of bone resorption in middle ear cholesteatoma.Material and methods: A total of 22 patients who underwent surgical treatment for middle ear cholesteatoma were recruited in the study. Protein expression of PTHrP and RANKL in middle ear cholesteatoma and normal postauricular skin was investigated by immunohistochemical staining. Correlations between bone resorption degree and expression of PTHrP and RANKL were also analyzed.Results: Protein expression of PTHrP and RANKL in cholesteatoma epithelium significantly increased when compared with normal postauricular skin epithelium. In cholesteatoma epithelium, a significantly positive association was observed between PTHrP and RANKL expression. Meanwhile, obviously positive correlations between protein expression of PTHrP and RANKL and bone resorption degree were discovered.Conclusions and significance: The increased protein expression of PTHrP and RANKL in cholesteatoma epithelium, and their associations with the degree of bone resorption, revealing that PTHrP might promote bone resorption process in middle ear cholesteatoma through RANKL signaling pathway.

Osteoclasts Modulate Bone Erosion in Cholesteatoma via RANKL Signaling

Cholesteatoma starts as a retraction of the tympanic membrane and expands into the middle ear, eroding the surrounding bone and causing hearing loss and other serious complications such as brain abscess and meningitis. Currently, the only effective treatment is complete surgical removal, but the recurrence rate is relatively high. In rheumatoid arthritis (RA), osteoclasts are known to be responsible for bone erosion and undergo differentiation and activation by receptor activator of NF-κB ligand (RANKL), which is secreted by synovial fibroblasts, T cells, and B cells. On the other hand, the mechanism of bone erosion in cholesteatoma is still controversial. In this study, we found that a significantly larger number of osteoclasts were observed on the eroded bone adjacent to cholesteatomas than in unaffected areas, and that fibroblasts in the cholesteatoma perimatrix expressed RANKL. We also investigated upstream transcription factors of RANKL using RNA sequencing results obtained via Ingenuity Pathways Analysis, a tool that identifies relevant targets in molecular biology systems. The concentrations of four candidate factors, namely interleukin-1β, interleukin-6, tumor necrosis factor α, and prostaglandin E2, were increased in cholesteatomas compared with normal skin. Furthermore, interleukin-1β was expressed in infiltrating inflammatory cells in the cholesteatoma perimatrix. This is the first report demonstrating that a larger-than-normal number of osteoclasts are present in cholesteatoma, and that the disease involves upregulation of factors related to osteoclast activation. Our study elucidates the molecular basis underlying bone erosion in cholesteatoma.

Spontaneous Resolution of Cholesteatoma in a Patient on Long-Term Infliximab

Objective:

To describe an observed case of spontaneous regression of cholesteatoma in a patient on chronic anti-tumor necrosis factor-alpha (TNF-a) therapy and inspire further research into the role of TNF-a in cholesteatoma.

Methods:

Clinical assessment of disease in a single-patient case report.

Results:

A 49-year-old woman suffered a severe case of Stevens-Johnson syndrome when she was 12 years old, leaving her with bilateral corneal opacification and tympanic membrane perforations with extensive cholesteatoma. For her corneal opacification, a corneal prosthesis was placed, which was complicated by a foreign body reaction necessitating long-term therapy with infliximab, a monoclonal antibody against TNF-a that is therapeutic in some chronic inflammatory diseases. She was otherwise healthy and took no other medications. While on infliximab, the patient had spontaneous and complete resolution of her cholesteatoma without any surgical intervention.

Conclusions:

This surprising case suggests that there may be a prominent role of TNF-a in cholesteatoma pathophysiology and that TNF-a may be an effective target for nonsurgical therapy.

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.

TREM-2 promotes acquired cholesteatoma-induced bone destruction by modulating TLR4 signaling pathway and osteoclasts activation

Triggering receptor expressed on myeloid cells (TREM) has been broadly studied in inflammatory disease. However, the expression and function of TREM-2 remain undiscovered in acquired cholesteatoma. The expression of TREM-2 was significantly higher in human acquired cholesteatoma than in normal skin from the external auditory canal, and its expression level was positively correlated with the severity of bone destruction. Furthermore, TREM-2 was mainly expressed on dendritic cells (DCs). In human acquired cholesteatoma, the expression of proinflammatory cytokines (IL-1β, TNF-α and IL-6) and matrix metalloproteinases (MMP-2, MMP-8 and MMP-9) were up-regulated, and their expression levels were positively correlated with TREM-2 expression. Osteoclasts were activated in human acquired cholesteatoma. In an animal model, TREM-2 was up-regulated in mice with experimentally acquired cholesteatoma. TREM-2 deficiency impaired the maturation of experimentally acquired cholesteatoma and protected against bone destruction induced by experimentally acquired cholesteatoma. Additional data showed that TREM-2 up-regulated IL-1β and IL-6 expression via TLR4 instead of the TLR2 signaling pathway and promoted MMP-2 and MMP-8 secretion and osteoclast activation in experimentally acquired cholesteatoma. Therefore, TREM-2 might enhance acquired cholesteatoma-induced bone destruction by amplifying the inflammatory response via TLR4 signaling pathways and promoting MMP secretion and osteoclast activation.

Pathogenesis and Bone Resorption in Acquired Cholesteatoma: Current Knowledge and Future Prospectives

Cholesteatoma is a cystic non tumorous lesion of the temporal bone that has the ability to destroy nearby structures by its power to cause bone resorption and as a result, fatal complications prevail. We aimed to conduct a comprehensive review for pathogenesis of acquired cholesteatoma, bone resorption mechanisms, and offer a future vision of this serious disease. We have reviewed different theories for pathogenesis of acquired cholesteatoma including the most relevant and updated ones with special emphasis on the mechanisms of bone resorption through Medline/PubMed research using the keywords 'aetiopathogenesis, bone resorption, acquired cholesteatoma, temporal bone, and cytokines.' In order to strengthen our study, we searched the reference lists of identified reviews. Cholesteatoma is a subject of debate among otolaryngologists since it was prescribed firstly. Over many decades, several theories were postulated for aetiopathogenesis of cholesteatoma with a tendency to follow more than one theory to explain the proper nature of that disease. Until now, the mechanism of bone resorption has yet to be more clarified. In the last century, a leap has occurred in the field of biomolecular cholesteatoma research which improved our knowledge about its pathophysiology and bone destructive mechanism. However, surgery is still the only available treatment. We conclude that discovery of new therapeutic choices for cholesteatoma other than surgery by the use of anti-growth, anti-proliferative, apoptotic agents as well as medications that antagonize osteoclastogenesis should be the main concern in the future clinical and experimental research work. Also, searching for predictors of the aggressiveness of cholesteatoma can affect the timing of intervention and prevent occurrence of complications.

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.

Osteoclasts are not activated in middle ear cholesteatoma

It is unclear whether osteoclasts are present and activated in cholesteatomas. We explored the expression of messenger RNA (mRNA) for osteoclast biomarkers and regulating factors in middle ear cholesteatomas to elucidate the level of osteoclast activity in this disease. Bone powder was collected from 14 patients with cholesteatomatous and noncholesteatomatous chronic otitis media during tympanomastoidectomy, separately from cortical bone of the mastoid (clean bone powder), from bone neighboring cholesteatoma (cholesteatomatous bone powder), and from bone of the air cells and antrum of noncholesteatomatous chronic otitis media patients (noncholesteatomatous bone powder). The samples collected were soaked in TRIzol reagent, and total RNA was extracted and purified by the acid guanidinium thiocyanate-phenol-chloroform method, followed by the use of magnetic bead technology. The sample was then subjected to quantitative reverse transcription polymerase chain reaction for receptor activator of nuclear factor κB (RANK), tartrate-resistant acid phosphatase (TRAP), cathepsin K (CTSK), osteoclast-associated receptor (OSCAR), calcitonin receptor (CALCR), matrix metalloproteinase 9 (MMP9), receptor activator of nuclear factor κB ligand (RANKL), and osteoprotegerin (OPG). There was no significant difference in the expression of TRAP, CTSK, OSCAR, CALCR, MMP9, or OPG among the clean, cholesteatomatous, and noncholesteatomatous bone powder. On the other hand, the expression of RANK and RANKL was significantly lower in the cholesteatomatous bone powder than in the noncholesteatomatous bone powder (P = 0.003 and P = 0.028, respectively). The RANKL mRNA/OPG mRNA ratio did not differ among the three samples. These results indicate that osteoclasts are unlikely to be activated in cholesteatomas. Bone resorption mechanisms not mediated by osteoclasts may need to be reappraised in cholesteatoma research in future studies.

Increased permeability of the epithelium of middle ear cholesteatoma

OBJECTIVE

We investigated the electrical impedance of and the expressions of tight junction molecules in the cholesteatoma epithelium to provide supporting evidence for the acid lysis theory of bone resorption in middle ear cholesteatoma.

METHODS

Study subjects were patients with primary acquired middle ear cholesteatoma and those with non-cholesteatomatous chronic otitis media who underwent tympanomastoidectomy. The electrical impedance of the cholesteatoma epithelium was measured during tympanomastoidectomy by loading alternating currents of 320 Hz and 30.7 kHz. The expressions of tricellulin (MARVELD2), claudin-1 (CLDN1) and claudin-3 (CLDN3) were examined by fluorescence immunohistochemistry and quantitative reverse transcription-polymerase chain reaction.

RESULTS

The electrical impedance of the cholesteatoma epithelium was significantly lower than that of the post-auricular skin and external auditory canal skin at both 320 Hz and 30.7 kHz. Immunoreactivity for MARVELD2, CLDN1 and CLDN3 was localised mainly in the granular layer, and to lesser degree, in the horny and spinous layers in both the cholesteatoma tissue and post-auricular skin. Fluorescence intensity was moderate for MARVELD2, weak for CLDN1 and strong for CLDN3. The expressions of MARVELD2, CLDN1 and CLDN3 mRNA were significantly lower in the cholesteatoma tissue than in the post-auricular skin.

CONCLUSIONS

These results indicate the increased permeability of the cholesteatoma epithelium and suggest that this change is, at least partially, dependent on the decrease in the expressions of the tight junction molecules. This evidence supports the acid lysis hypothesis of bone resorption in cholesteatoma.

TLR4 drives the pathogenesis of acquired cholesteatoma by promoting local inflammation and bone destruction

Acquired cholesteatoma is a chronic inflammatory disease characterized by both hyperkeratinized squamous epithelial overgrowth and bone destruction. Toll-like receptor (TLR) activation and subsequent inflammatory cytokine production are closely associated with inflammatory bone disease. However, the expression and function of TLRs in cholesteatoma remain unclear.We observed inflammatory cell infiltration of the matrix and prematrix of human acquired cholesteatoma, as well as dramatically increased expression of TLR4 and the pro-inflammatory cytokines TNF-α and IL-1β. TLR2 exhibited an up-regulation that was not statistically significant. TLR4 expression in human acquired cholesteatoma correlated with disease severity; the number of TLR4-positive cells increased with an increased degree of cholesteatoma, invasion, bone destruction, and hearing loss. Moreover, TLR4 deficiency was protective against experimental acquired cholesteatoma-driven bone destruction and hearing loss, as it reduced local TNF-α and IL-1β expression and impaired osteoclast formation by decreasing expression of the osteoclast effectors receptor activator of nuclear factor (NF)-κB ligand (RANKL) and tartrate-resistant acid phosphatase (TRAP). TLR2 deficiency did not relieve disease severity, inflammatory responses, or osteoclast formation. Moreover, neither TLR2 nor TLR4 deficiency had an effect on antimicrobial peptides, inducible iNOS,BD-2 expression or bacterial clearance. Therefore, TLR4 may promote cholesteatoma-induced bone destruction and deafness by enhancing inflammatory responses and osteoclastogenesis.

Bacterial Infections and Osteoclastogenesis Regulators in Men and Women with Cholesteatoma

One of the most distinct features of middle ear cholesteatoma is bone destruction. Aetiology of cholesteatoma is thought to be multifactorial. Endotoxins produced by bacteria are thought to initiate the inflammation process in the middle ear leading to cholesteatoma. There are physiological differences in bone metabolism between men and women. The aim of our study was the immunohistochemical evaluation of the contents of two key components of the OPG/RANK/RANKL triad-RANKL and OPG in cholesteatoma, to analyse if there are any differences between the sexes and to evaluate the bacteria species isolated from cholesteatoma just before surgical treatment and to evaluate their plausible influence on the expression of OPG and RANKL in cholesteatoma. Twenty-one adult patients with acquired cholesteatoma who underwent surgery were analysed. There were no statistically significant differences in the expression of both regulators of osteoclastogenesis between the sexes. In 38.1 % patients cholesteatoma was not infected, whereas in 61.9 % patients various bacterial infections or mycosis were found. The most frequently isolated species was Pseudomonas aeruginosa (14.29 % infections) followed by Staphylococcus aureus (9.52 % infections). There were no statistically significant differences in expression of both OPG and RANKL between uninfected and infected cholesteatomas.

Expression levels of receptor activator of nuclear factor-κB ligand and osteoprotegerin are associated with middle ear cholesteatoma risk

CONCLUSION

Overexpression of receptor activator of nuclear factor-κB ligand (RANKL) and low expression of osteoprotegerin (OPG) are typical features in middle ear cholesteatoma patients. The altered RANKL/OPG protein ratio suggests that alterations in the RANKL-OPG pathway may be major factors in the pathogenesis of middle ear cholesteatoma.

OBJECTIVE

Our meta-analysis explored the contribution of one important cytokine pathway, the RANKL and OPG pathway, in the development of middle ear cholesteatoma.

METHODS

We screened Embase, the Cochrane Library, CISCOM, CINAHL, Google Scholar, China BioMedicine, China National Knowledge Infrastructure, PubMed, and Web of Science for relevant articles. RANKL expression and ratio of RANKL/OPG were analyzed using Comprehensive Meta-Analysis Version 2 software.

RESULTS

The electronic literature search identified five studies that contained information on the correlation of RANKL and OPG expression with middle ear cholesteatoma. Increased RANKL expression positively correlated with middle ear cholesteatoma, while OPG expression showed an inverse association (p < 0.05). The ratio of RANKL/OPG in middle ear cholesteatoma cases was higher than in healthy controls, indicating that our observations are applicable to each individual case. Subgroup analysis based on country of study revealed that OPG levels decreased in China and Korea, and high RANKL expression was found in Poland, China, and Korea (all p < 0.05).

Large-scale proteomics differentiates cholesteatoma from surrounding tissues and identifies novel proteins related to the pathogenesis

Cholesteatoma is the growth of keratinizing squamous epithelium in the middle ear. It is associated with severe complications and has a poorly understood etiopathogenesis. Here, we present the results from extensive bioinformatics analyses of the first large-scale proteomic investigation of cholesteatoma. The purpose of this study was to take an unbiased approach to identifying alterations in protein expression and in biological processes, in order to explain the characteristic phenotype of this skin-derived tumor. Five different human tissue types (cholesteatoma, neck of cholesteatoma, tympanic membrane, external auditory canal skin, and middle ear mucosa) were analyzed. More than 2,400 unique proteins were identified using nanoLC-MS/MS based proteomics (data deposited to the ProteomeXchange), and 295 proteins were found to be differentially regulated in cholesteatoma. Validation analyses were performed by SRM mass spectrometry. Proteins found to be up- or down-regulated in cholesteatoma were analyzed using Ingenuity Pathway Analysis and clustered into functional groups, for which activation state and associations to disease processes were predicted. Cholesteatoma contained high levels of pro-inflammatory S100 proteins, such as S100A7A and S100A7. Several proteases, such as ELANE, were up-regulated, whereas extracellular matrix proteins, such as COL18A1 and NID2, were under-represented. This may lead to alterations in integrity and differentiation of the tissue (as suggested by the up-regulation of KRT4 in the cholesteatoma). The presented data on the differential protein composition in cholesteatoma corroborate previous studies, highlight novel protein functionalities involved in the pathogenesis, and identify new areas for targeted research that hold therapeutic potential for the disease.

Ultrastructual morphology of juvenile psammomatoid ossifying fibroma

We investigated the ultrastructural morphology of the hard tissue in a fibro-osseous lesion. Bone samples were obtained from a juvenile psammomatoid ossifying fibroma and were observed under a scanning electron microscope. The lesion had a spongy lamellar structure containing bony tissue. On histological examination, resorbing preexisting lamellar bone associated with a large number of cathepsin K-positive osteoclasts was confirmed. Scanning electron microscopy revealed the bony material to have a cribriform structure and to indicate resorption related to osteoclasts throughout the tumor. These characteristic findings revealed the presence of active bony reconstruction and destruction in this lesion. The spongy calcified structure observed by scanning electron microscopy expressed the characteristic ground glass appearance in computed tomography of this patient. This remarkable activation of osteoclasts may deeply relate to characteristic calcified structure in this lesion. Observation of hard tissue structure under a scanning electron microscope may shed light on the pathology of fibro-osseous lesions in the head and neck.

Expression of tumor necrosis factor-α, interleukin-1α, interleukin-6 and interleukin-10 in chronic otitis media with bone osteolysis

The purpose of this study was to evaluate the expression of proinflammatory and immunoregulatory cytokines in chronic otitis media. The expression levels of TNF-α, IL-1α, IL-6 and IL-10 were determined by Western blot analysis of tissue samples obtained during ear surgery. The expression levels of TNF-α, IL-1α and IL-6 in cholesteatoma tissues were substantially higher compared to those determined in the granulation tissue. The highest levels of TNF-α, IL-1 and IL-6 proteins were observed in patients with bone destruction. There were no significant differences in the expression of IL-10 levels in cholesteatoma and normal skin, but in the granulation tissue its level was substantially higher. The level of IL-10 in cholesteatoma tissues inversely correlated with the expression of proinflammatory cytokines, the degree of bone destruction and cholesteatoma invasion. Increased expressions of TNF-α, IL-1α and IL-6 in chronic otitis media and a strong positive correlation between these cytokine levels and the degree of bone destruction indicate the destructive behavior of cholesteatoma or granulation tissue.

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 Gdańsk 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.

Cholesteatoma growth and proliferation: posttranscriptional regulation by microRNA-21

OBJECTIVES

The goal of this study was to identify novel regulatory mechanisms controlling the growth and proliferation of cholesteatoma. Specifically, the potential role of microRNAs, regulators of protein translation, was studied in cholesteatoma.

STUDY DESIGN

This study represents a molecular biologic investigation characterizing and comparing microRNA and protein expression in cholesteatoma and normal postauricular skin.

METHODS

Cholesteatoma and normal skin were taken from patients at the time of surgery. Tissue was processed for RNA and protein extraction. Real-time reverse-transcriptase-polymerase chain reaction was used to assess levels of human microRNAs, reverse-transcriptase-polymerase chain reaction was used to confirm the presence of upstream regulators, and Western blot analyses were used to assess levels of downstream target proteins.

RESULTS

Among the microRNAs investigated, human microRNA-21 (hsa-miR-21) showed a 4.4-fold higher expression in cholesteatoma as compared with normal skin (p = 0.0011). The downstream targets of hsa-miR-21, PTEN and programmed cell death 4, were found to be greatly reduced in 3 of 4 cholesteatoma samples. Proposed upstream regulators of hsa-miR-21 expression (CD14, interleukin 6R, gp130, and signal transducer and activator of transcription 3) were present in all cholesteatoma tissues.

CONCLUSION

MicroRNAs represent powerful regulators of protein translation, and their dysregulation has been implicated in many neoplastic diseases. This study specifically identified up-regulation of hsa-miR-21 concurrent with down-regulation of potent tumor suppressor proteins PTEN and programmed cell death 4. These proteins control aspects of apoptosis, proliferation, invasion, and migration. The results of this study were used to develop a model for cholesteatoma proliferation through microRNA dysregulation. This model can serve as a template for further study into potential RNA-based therapies for the treatment of cholesteatoma.

Testing of the OMERACT 8 Draft Validation Criteria for a Soluble Biomarker Reflecting Structural Damage in Rheumatoid Arthritis: A Systematic Literature Search on 5 Candidate Biomarkers

Objective.

To test the OMERACT 8 draft validation criteria for soluble biomarkers by assessing the strength of literature evidence in support of 5 candidate biomarkers.

Methods.

A systematic literature search was conducted on the 5 soluble biomarkers RANKL, osteoprotegerin (OPG), matrix metalloprotease (MMP-3), urine C-telopeptide of types I and II collagen (U-CTX-I and U CTX-II), focusing on the 14 OMERACT 8 criteria. Two electronic voting exercises were conducted to address: (1) strength of evidence for each biomarker as reflecting structural damage according to each individual criterion and the importance of each individual criterion; (2) overall strength of evidence in support of each of the 5 candidate biomarkers as reflecting structural damage endpoints in rheumatoid arthritis (RA) and identification of omissions to the criteria set.

Results.

The search identified 111 articles. The strength of evidence in support of these biomarkers reflecting structural damage was low for all biomarkers and was rated highest for U-CTX-II [score of 6.5 (numerical rating scale 0–10)]. The lowest scores for retention of specific criteria in the draft set went to criteria that refer to the importance of animal studies, correlations with other biomarkers reflecting damage, and an understanding of the metabolism of the biomarker.

Conclusion.

Evidence in support of any of the 5 tested biomarkers (MMP-3, CTX-I, CTX-II, OPG, RANKL) was inadequate to allow their substitution for radiographic endpoints in RA. Three of the criteria in the draft criteria set might not be required, but few omissions were identified.