Advancements in prevention and intervention of sensorineural hearing loss.

The inner ear is a complex and difficult organ to study, and sensorineural hearing loss (SNHL) is a multifactorial sensorineural disorder with characteristics of impaired speech discrimination, recognition, sound detection, and localization. Till now, SNHL is recognized as an incurable disease because the potential mechanisms underlying SNHL have not been elucidated. The risk of developing SNHL is no longer viewed as primarily due to environmental factors. Instead, SNHL seems to result from a complicated interplay of genetic and environmental factors affecting numerous fundamental cellular processes. The complexity of SNHL is presented as an inability to make an early diagnosis at the earliest stages of the disease and difficulties in the management of symptoms during the process. To date, there are no treatments that slow the neurodegenerative process. In this article, we review the recent advances about SHNL and discuss the complexities and challenges of prevention and intervention of SNHL.

Effectiveness of salvage intratympanic dexamethasone treatment for refractory sudden sensorineural hearing loss classified by audiogram patterns.

BACKGROUND: Intratympanic dexamethasone is commonly conducted to treat refractory sudden sensorineural hearing loss (RSSNHL). However, no consensus has been reached on its effectiveness. OBJECTIVES: The study aimed to evaluate the effectiveness of otoendoscope-assisted salvage intratympanic dexamethasone treatment (IDT) on RSSNHL with different audiogram patterns after failure of initial therapy. MATERIAL AND METHODS: A total of 108 patients with unilateral RSSNHL were classified into 4 groups according to audiogram patterns. Hearing results were evaluated by pure-tone audiometry (PTA), which was performed at baseline and one month after otoendoscope-assisted salvage IDT. The effectiveness of otoendoscope-assisted salvage IDT was assessed in each group. RESULTS: The efficiency in low-frequency, high-frequency, flat, and deaf group was 48%, 24.1%, 46.2%, 17.9%, respectively. The efficacy did not differ between the high-frequency and deaf group. Notably, the efficacy in the low-frequency and flat group was significantly higher than that in the deaf group. CONCLUSIONS: Otoendoscope-assisted salvage IDT is a safe and effective treatment for RSSNHL. This treatment provided better results for patients with low-frequency damaged and flat curve audiogram than patients with other audiogram patterns. SIGNIFICANCE: Audiogram patterns should be considered in the clinical management of patients with RSSHNL prior to salvage IDT.

Yolk sac tumor of ear: a case report and literature review of the last 30 years.

Extra-gonadal pure yolk sac tumor of the ear is very rare. We report a case of a yolk sac tumor of the ear and review the English literature in PubMed. The initial complaint was a mass protruding out of the external auditory canal. Computed tomography (CT) showed a large irregularly enhancing isodense mass lesion measuring 42*16 mm in the right external auditory canal, the right mastoid process, and extending to the right back parapharyngeal space with unclear border. Laboratory studies revealed that serum alpha fetoprotein (AFP) was significantly elevated at 664.60 ng/ml (range, 0 to 25 ng/ml), and neuron-specific enolase (NSE) was 28.3 ng/ml (range, 0 to 16.3 ng/ml). After finishing 6 cycles of chemotherapy, the patient underwent a total resection of yolk sac tumor of the ear. In addition, we review the English literature of the yolk sac tumor of the ear.

HB-EGF expression as a potential biomarker of acquired middle ear cholesteatoma.

CONCLUSIONS: The heparin-binding epidermal growth factor-like growth factor (HB-EGF) plays an essential role in the development and invasiveness of cholesteatoma. This study may help to realize the molecular mechanisms underlying the pathogenesis of cholesteatoma and make HB-EGF a promising target for drug intervention of cholesteatoma. OBJECTIVE: To detect HB-EGF expression in human surgical specimens of acquired middle ear cholesteatoma and analyze its functional role as a regulator of epithelial keratinocytes hyperproliferation. METHODS: A total of 34 patients who underwent surgical treatment for middle ear cholesteatoma were recruited in the study. The mRNA and protein expression of HB-EGF in middle ear cholesteatoma tissues and normal postauricular skin tissues was investigated by real-time quantitative reverse-transcription-polymerase chain reaction (RT-qPCR), immunohistochemical staining, and western blot. The correlation between bone resorption degree and HB-EGF expression was also analyzed. RESULTS: On average, compared with normal postauricular skin, expression of HB-EGF mRNA in the cholesteatoma epithelium was significantly elevated 2.41-fold by RT-qPCR, and HB-EGF protein significantly upregulated 2.32-fold by western blot. Positive HB-EGF immunostaining observed in the basal and suprabasal layers of cholesteatoma epithelium was significantly stronger than in normal postauricular skin. Meanwhile, an obviously positive correlation between HB-EGF protein expression and bone resorption degree was discovered.

DAPT mediates atoh1 expression to induce hair cell-like cells.

Hearing loss is currently an incurable degenerative disease characterized by a paucity of hair cells (HCs), which cannot be spontaneously replaced in mammals. Recent technological advancements in gene therapy and local drug delivery have shed new light for hearing loss. Atoh1, also known as Math1, Hath1, and Cath1, is a proneural basic helix-loop-helix (bHLH) transcription factor that is essential for HC differentiation. At various stages in development, Atoh1 activity is sufficient to drive HC differentiation in the cochlea. Thus, Atoh1 related gene therapy is the most promising option for HC induction. DAPT, an inhibitor of Notch signaling, enhances the expression of Atoh1 indirectly, which in turn promotes the induction of a HC fate. Here, we show that DAPT cooperates with Atoh1 to synergistically promote HC fate in ependymal cells in vitro and promote hair cell regeneration in the cultured basilar membrane (BM) which mimics the microenvironment in vivo. Taken together, our findings demonstrated that DAPT is sufficient to induce HC-like cells via enhancing of the expression of Atoh1 to inhibit the progression of HC apoptosis and to induce new HC formation.

Acquired cholesteatoma epithelial hyperproliferation: Roles of cell proliferation signal pathways.

OBJECTIVES/HYPOTHESIS: To review the recent cell proliferation signal pathways in the etiopathogenesis of acquired middle ear cholesteatoma. DATA SOURCES: PubMed (to September 2015). REVIEW METHODS: Articles about cell proliferation signal pathways in the etiopathogenesis of acquired cholesteatoma and treatment advances were searched in the PubMed database, from which 73 were included in this review. RESULTS: The exact underlying cellular and molecular mechanism of acquired cholesteatoma still remains unknown. Recent research tends to regard the proliferation of cholesteatoma epithelial cells as the mechanism of cholesteatoma pathogenesis. Cell proliferation signal pathways including epidermal growth factor receptor/phosphoinositide 3-kinase/protein kinase B signal pathway, mitogen-activated protein kinase signal pathway, interleukin-6/signal transducer and activator of transcription 3 signal pathway, inhibitor of DNA binding/differentiation-1/nuclear factor-κB/cyclinD1 signal pathway, microRNA-mediated proliferation signal pathway, and keratinocyte growth factor/keratinocyte growth factor receptor signal pathway have been proven to play important roles in acquired middle ear cholesteatoma. CONCLUSIONS: This review outlines the main biological properties of certain cell proliferation signal pathways, aiming to facilitate the development of potential therapeutic targets for intratympanic drug therapy for the nonsurgical or complementary treatment of cholesteatoma. LEVEL OF EVIDENCE: NA Laryngoscope, 126:1923-1930, 2016.

[Clinical multi-center study on the treatment of sudden sensorineural hearing loss accompanied with feeling of ear fullness].

OBJECTIVE: To investigate the therapeutic effect of drug treatment for patients with sudden sensorineural hearing loss (SSNHL) accompanied with feeling of ear fullness (FEF). METHODS: A prospective clinical multicenter research was carried out from August 2007 to October 2011. SSNHL patients aged between 18 to 65 years old and accepted no medication were recruited, with a duration less than two weeks. The patients were divided into four types according to the hearing curve: type A was acute SSNHL in low tone frequencies, type B was acute SSNHL in high tone frequencies, type C was acute SSNHL in all frequencies, and type D was total deafness. Each type was subdivided into two groups by the accompaniment of SEF or not. And each type had four different treatment programs, based on the unified designed randomized table. All patients were followed up for four weeks from the initial examination. RESULTS: A total of 1 024 cases with single side SSNHL were recruited in the study from 33 hospitals in China, including 565 cases accompanied with FEF (55.18%), and 459 cases without FEF (44.82%). By classification of audiogram, 205 cases were type A (20.20%), of whom 122 were accompanied with FEF (59.51%); 141 cases belonged to type B (13.77%), of whom 74 were accompanied with FEF (52.48%); 402 cases were type C (39.25%), of whom 229 were accompanied with FEF (56.97%); and 276 cases were classified as type D (26.95%), of whom 140 were accompanied with FEF (50.72%). No significant difference was observed in total effective rate between the SSNHL patients accompanied with FEF or not in four acoustic types (P > 0.05). Among four acoustic types, the clinical cure rate of patients accompanied with FEF in type A was 93.44%, ranking the first; followed by 84.28% for type C; 75.71% for type D; and 70.27% for type B, respectively. CONCLUSIONS: The therapeutic effect for patients accompanied with FEF in type A is satisfactory. The presence of FEF do not impact the therapeutic effect for SSNHL patients.

Intratympanic dexamethasone injections for refractory Meniere' s disease.

Intratympanic injections or titration is a potential medical therapeutic strategy for patients with incurable inner ear diseases. Dexamethasone represent an attractive steroid source in intratympanic steroids strategies in the treatment of inner ear disorders. Here, we evaluated the effectiveness of intratympanic dexamethasone injections (IDI) in outpatients with refractory Meniere's disease (MD). Vestibular function measured by Vestibular Ocular Reflex (VOR) gain and caloric test revealed that 21 outpatients out of 43 (48.8%) had complete sufficient vertigo control, while 9 (20.9%) of them were attached to fundamental manipulation. Out of the 13 remaining outpatients, 4 (9.3%) had a limit control and 9 had less modification. Therefore, 5 of 9 received re-treatment with IDI and 2 of 9 patients were administered ablative treatment with gentamicin. Meanwhile, audiology data suggested that 3 (7.0%), 4 (9.3%), 32 (74.4%), 4 (9.3%) patients were attached to the level of A, B, C, D, respectively. Furthermore, the symptom of tinnitus in 5 outpatients vanished, 21 (48.8%) diminished, 10 (23.3%) invariable, 7 (16.3%) aggravated. In 4 of 24 cases (16.7%), aural fullness disappeared after IDI, when the aural fullness was alleviated in 11 cases (45.8%) even intensive in 9 patients (37.5%). Together, our results demonstrate that intratympanic dexamethasone injection, as an effective therapeutic strategy for refractory Meniere's disease, could either be used for cascade therapy preoperation or used for patients who couldn't accept the surgery.

Activation of the IL-6/JAK/STAT3 signaling pathway in human middle ear cholesteatoma epithelium.

Interleukin-6 (IL-6) is one of the most important cytokines which has been shown to play a critical role in the pathogenesis of cholesteatoma. In this study, we aimed to investigate the expression of interleukin-6 (IL-6) and phosphorylated signal transducer and activator of transcription 3 (p-STAT3) in middle ear cholesteatoma epithelium in an effort to determine the role of IL-6/JAK/STAT3 signaling pathway in the pathogenesis of cholesteatoma. Immunohistochemistry was used to examine the expression of IL-6 and p-STAT3 in 25 human middle ear cholesteatoma samples and 15 normal external auditory canal (EAC) epithelium specimens. We also analyzed the relation of IL-6 and p-STAT3 expression levels to the degree of bone destruction in cholesteatoma. We found that the expression of IL-6 and p-STAT3 were significantly higher in cholesteatoma epithelium than in normal EAC epithelium (p<0.05). In cholesteatoma epithelium, a significant positive association was observed between IL-6 and p-STAT3 expression (p<0.05). However, no significant relationships were observed between the degree of bone destruction and the levels of IL-6 and p-STAT3 expression (p>0.05). To conclude, our results support the concept that IL-6/JAK/STAT3 signaling pathway is active and may play an important role in the mechanisms of epithelial hyper-proliferation responsible for cholesteatoma.

The role of EGFR/PI3K/Akt/cyclinD1 signaling pathway in acquired middle ear cholesteatoma.

Cholesteatoma is a benign keratinizing and hyper proliferative squamous epithelial lesion of the temporal bone. Epidermal growth factor (EGF) is one of the most important cytokines which has been shown to play a critical role in cholesteatoma. In this investigation, we studied the effects of EGF on the proliferation of keratinocytes and EGF-mediated signaling pathways underlying the pathogenesis of cholesteatoma. We examined the expressions of phosphorylated EGF receptor (p-EGFR), phosphorylated Akt (p-Akt), cyclinD1, and proliferating cell nuclear antigen (PCNA) in 40 cholesteatoma samples and 20 samples of normal external auditory canal (EAC) epithelium by immunohistochemical method. Furthermore, in vitro studies were performed to investigate EGF-induced downstream signaling pathways in primary external auditory canal keratinocytes (EACKs). The expressions of p-EGFR, p-Akt, cyclinD1, and PCNA in cholesteatoma epithelium were significantly increased when compared with those of control subjects. We also demonstrated that EGF led to the activation of the EGFR/PI3K/Akt/cyclinD1 signaling pathway, which played a critical role in EGF-induced cell proliferation and cell cycle progression of EACKs. Both EGFR inhibitor AG1478 and PI3K inhibitor wortmannin inhibited the EGF-induced EGFR/PI3K/Akt/cyclinD1 signaling pathway concomitantly with inhibition of cell proliferation and cell cycle progression of EACKs. Taken together, our data suggest that the EGFR/PI3K/Akt/cyclinD1 signaling pathway is active in cholesteatoma and may play a crucial role in cholesteatoma epithelial hyper-proliferation. This study will facilitate the development of potential therapeutic targets for intratympanic drug therapy for cholesteatoma.

Intracerebral neural stem cell transplantation improved the auditory of mice with presbycusis.

Stem cell-based regenerative therapy is a potential cellular therapeutic strategy for patients with incurable brain diseases. Embryonic neural stem cells (NSCs) represent an attractive cell source in regenerative medicine strategies in the treatment of diseased brains. Here, we assess the capability of intracerebral embryonic NSCs transplantation for C57BL/6J mice with presbycusis in vivo. Morphology analyses revealed that the neuronal rate of apoptosis was lower in the aged group (10 months of age) but not in the young group (2 months of age) after NSCs transplantation, while the electrophysiological data suggest that the Auditory Brain Stem Response (ABR) threshold was significantly decreased in the aged group at 2 weeks and 3 weeks after transplantation. By contrast, there was no difference in the aged group at 4 weeks post-transplantation or in the young group at any time post-transplantation. Furthermore, immunofluorescence experiments showed that NSCs differentiated into neurons that engrafted and migrated to the brain, even to sites of lesions. Together, our results demonstrate that NSCs transplantation improve the auditory of C57BL/6J mice with presbycusis.