Large-scale annotated dataset for cochlear hair cell detection and classification.

Our sense of hearing is mediated by cochlear hair cells, of which there are two types organized in one row of inner hair cells and three rows of outer hair cells. Each cochlea contains 5-15 thousand terminally differentiated hair cells, and their survival is essential for hearing as they do not regenerate after insult. It is often desirable in hearing research to quantify the number of hair cells within cochlear samples, in both pathological conditions, and in response to treatment. Machine learning can be used to automate the quantification process but requires a vast and diverse dataset for effective training. In this study, we present a large collection of annotated cochlear hair-cell datasets, labeled with commonly used hair-cell markers and imaged using various fluorescence microscopy techniques. The collection includes samples from mouse, rat, guinea pig, pig, primate, and human cochlear tissue, from normal conditions and following in-vivo and in-vitro ototoxic drug application. The dataset includes over 107,000 hair cells which have been identified and annotated as either inner or outer hair cells. This dataset is the result of a collaborative effort from multiple laboratories and has been carefully curated to represent a variety of imaging techniques. With suggested usage parameters and a well-described annotation procedure, this collection can facilitate the development of generalizable cochlear hair-cell detection models or serve as a starting point for fine-tuning models for other analysis tasks. By providing this dataset, we aim to give other hearing research groups the opportunity to develop their own tools with which to analyze cochlear imaging data more fully, accurately, and with greater ease.

Signaling pathways regulating the immune function of cochlear supporting cells and their involvement in cochlear pathophysiology.

The inner ear, including the cochlea, used to be regarded as an immune-privileged site because of its immunologically isolated environment caused by the blood-labyrinthine barrier. Cochlear resident macrophages, which originate from the yolk sac or fetal liver during the embryonic stage and are maintained after birth, are distributed throughout various regions of the cochlear duct. Intriguingly, these cells are absent in the organ of Corti, where hair cells (HCs) and supporting cells (SCs) are located, except for a limited number of ionized calcium-binding adapter molecule 1 (Iba1)-positive cells. Instead, SCs exert glial functions varying from a quiescent to an emergency state. Notably, SCs acquire the nature of macrophages and begin to secrete inflammatory cytokines during viral infection in the organ of Corti, which is ostensibly unprotected owing to the lack of general resident macrophages. This review provides an overview of both positive and negative functions of SCs enabled to acquire macrophage phenotypes upon viral infection focusing on the signaling pathways that regulate these functions. The former function protects HCs from viral infection by inducting type I interferons, and the latter function induces HC death by necroptosis, leading to sensorineural hearing loss. Thus, SCs play contradictory roles as immune cells with acquired macrophage phenotypes; thereby, they are favorable and unfavorable to HCs, which play a pivotal role in hearing function.

Large-scale annotated dataset for cochlear hair cell detection and classification.

Our sense of hearing is mediated by cochlear hair cells, localized within the sensory epithelium called the organ of Corti. There are two types of hair cells in the cochlea, which are organized in one row of inner hair cells and three rows of outer hair cells. Each cochlea contains a few thousands of hair cells, and their survival is essential for our perception of sound because they are terminally differentiated and do not regenerate after insult. It is often desirable in hearing research to quantify the number of hair cells within cochlear samples, in both pathological conditions, and in response to treatment. However, the sheer number of cells along the cochlea makes manual quantification impractical. Machine learning can be used to overcome this challenge by automating the quantification process but requires a vast and diverse dataset for effective training. In this study, we present a large collection of annotated cochlear hair-cell datasets, labeled with commonly used hair-cell markers and imaged using various fluorescence microscopy techniques. The collection includes samples from mouse, human, pig and guinea pig cochlear tissue, from normal conditions and following in-vivo and in-vitro ototoxic drug application. The dataset includes over 90'000 hair cells, all of which have been manually identified and annotated as one of two cell types: inner hair cells and outer hair cells. This dataset is the result of a collaborative effort from multiple laboratories and has been carefully curated to represent a variety of imaging techniques. With suggested usage parameters and a well-described annotation procedure, this collection can facilitate the development of generalizable cochlear hair cell detection models or serve as a starting point for fine-tuning models for other analysis tasks. By providing this dataset, we aim to supply other groups within the hearing research community with the opportunity to develop their own tools with which to analyze cochlear imaging data more fully, accurately, and with greater ease.

Virus-infection in cochlear supporting cells induces audiosensory receptor hair cell death by TRAIL-induced necroptosis.

Although sensorineural hearing loss (SHL) is relatively common, its cause has not been identified in most cases. Previous studies have suggested that viral infection is a major cause of SHL, especially sudden SHL, but the system that protects against pathogens in the inner ear, which is isolated by the blood-labyrinthine barrier, remains poorly understood. We recently showed that, as audiosensory receptor cells, cochlear hair cells (HCs) are protected by surrounding accessory supporting cells (SCs) and greater epithelial ridge (GER or Kölliker's organ) cells (GERCs) against viral infections. Here, we found that virus-infected SCs and GERCs induce HC death via production of the tumour necrosis factor-related apoptosis-inducing ligand (TRAIL). Notably, the HCs expressed the TRAIL death receptors (DR) DR4 and DR5, and virus-induced HC death was suppressed by TRAIL-neutralizing antibodies. TRAIL-induced HC death was not caused by apoptosis, and was inhibited by necroptosis inhibitors. Moreover, corticosteroids, the only effective drug for SHL, inhibited the virus-induced transformation of SCs and GERCs into macrophage-like cells and HC death, while macrophage depletion also inhibited virus-induced HC death. These results reveal a novel mechanism underlying virus-induced HC death in the cochlear sensory epithelium and suggest a possible target for preventing virus-induced SHL.

Norrie disease protein is essential for cochlear hair cell maturation.

Mutations in the gene for Norrie disease protein (Ndp) cause syndromic deafness and blindness. We show here that cochlear function in an Ndp knockout mouse deteriorated with age: At P3-P4, hair cells (HCs) showed progressive loss of Pou4f3 and Gfi1, key transcription factors for HC maturation, and Myo7a, a specialized myosin required for normal function of HC stereocilia. Loss of expression of these genes correlated to increasing HC loss and profound hearing loss by 2 mo. We show that overexpression of the Ndp gene in neonatal supporting cells or, remarkably, up-regulation of canonical Wnt signaling in HCs rescued HCs and cochlear function. We conclude that Ndp secreted from supporting cells orchestrates a transcriptional network for the maintenance and survival of HCs and that increasing the level of ß-catenin, the intracellular effector of Wnt signaling, is sufficient to replace the functional requirement for Ndp in the cochlea.

An antibody to RGMa promotes regeneration of cochlear synapses after noise exposure.

Auditory neuropathy is caused by the loss of afferent input to the brainstem via the components of the neural pathway comprising inner hair cells and the first order neurons of the spiral ganglion. Recent work has identified the synapse between cochlear primary afferent neurons and sensory hair cells as a particularly vulnerable component of this pathway. Loss of these synapses due to noise exposure or aging results in the pathology identified as hidden hearing loss, an initial stage of cochlear dysfunction that goes undetected in standard hearing tests. We show here that repulsive axonal guidance molecule a (RGMa) acts to prevent regrowth and synaptogenesis of peripheral auditory nerve fibers with inner hair cells. Treatment of noise-exposed animals with an anti-RGMa blocking antibody regenerated inner hair cell synapses and resulted in recovery of wave-I amplitude of the auditory brainstem response, indicating effective reversal of synaptopathy.

Cochlear supporting cells function as macrophage-like cells and protect audiosensory receptor hair cells from pathogens.

To protect the audiosensory organ from tissue damage from the immune system, the inner ear is separated from the circulating immune system by the blood-labyrinth barrier, which was previously considered an immune-privileged site. Recent studies have shown that macrophages are distributed in the cochlea, especially in the spiral ligament, spiral ganglion, and stria vascularis; however, the direct pathogen defence mechanism used by audiosensory receptor hair cells (HCs) has remained obscure. Here, we show that HCs are protected from pathogens by surrounding accessory supporting cells (SCs) and greater epithelial ridge (GER or Kölliker's organ) cells (GERCs). In isolated murine cochlear sensory epithelium, we established Theiler's murine encephalomyelitis virus, which infected the SCs and GERCs, but very few HCs. The virus-infected SCs produced interferon (IFN)-α/ß, and the viruses efficiently infected the HCs in the IFN-α/ß receptor-null sensory epithelium. Interestingly, the virus-infected SCs and GERCs expressed macrophage marker proteins and were eliminated from the cell layer by cell detachment. Moreover, lipopolysaccharide induced phagocytosis of the SCs without cell detachment, and the SCs phagocytosed the bacteria. These results reveal that SCs function as macrophage-like cells, protect adjacent HCs from pathogens, and provide a novel anti-infection inner ear immune system.

Activation of IGF1 Signaling in the Cochlea Induces the Transcription of Its Mediators During the Protection of Cochlear Hair Cells Against Aminoglycoside.

HYPOTHESIS: Transcription of the Erk and Akt genes and phosphorylation of their products are promoted by insulin-like growth factor 1 (IGF1) during hair cell protection. BACKGROUND: IGF1 protects mammalian hair cells in animal models from various types of damage, including aminoglycoside. Moreover, clinical trials have revealed that IGF1 was effective for idiopathic sudden sensorineural hearing loss. In this process, activation of the downstream of IGF1 signaling, including the phosphorylation of extracellular signal-regulated kinase (ERK) and AKT proteins, is involved. However, the regulation of IGF1 signaling mediators at the transcriptional level has not been studied. METHODS: We used a neomycin damage model on neonatal mouse cochlear explant culture. Explants established from neonatal mice were treated with either neomycin alone or neomycin and IGF1. The expression levels of IGF1 signaling mediator genes, Akt1, Mapk3, and Mapk1, in the explants were compared using quantitative reverse transcriptase-polymerase chain reaction at several time points. Inhibitors of IGF1 signaling were added to confirm that this observation was dependent on IGF1 signaling. RESULTS: The expression levels of all genes tested were significantly upregulated in neomycin+IGF1 treatment samples (p < 0.0001, analysis of variance [ANOVA]). Addition of inhibitors of IGF1 signaling significantly attenuated the upregulation of expression (p < 0.0001, ANOVA). CONCLUSIONS: IGF1 treatment upregulates the expression of its mediator genes during the protection of hair cells against aminoglycoside. The regulation of mediator gene expression may serve as a novel treatment for sensorineural hearing loss.

Is otolithic vertigo accompanied by hearing loss caused by sacculocochlear endolymphatic hydrops?

CONCLUSION: Otolithic vertigo is sometimes accompanied by hearing loss. Otolithic vertigo accompanied by hearing loss seems to be caused by sacculocochlear endolymphatic hydrops. OBJECTIVES: To clarify the lesion site and pathophysiology of otolithic vertigo (OV) accompanied by hearing loss. METHODS: The clinical records of four patients (two men and two women) that had been diagnosed with OV accompanied by hearing loss according to pre-determined diagnostic criteria were reviewed. RESULTS: The patients' main symptoms involved a sensation of movement in the pitch plane. All of the patients had low frequency-dominant hearing loss and either exhibited decreased cervical vestibular evoked myogenic potentials (cVEMP) or did not produce cVEMP. Two patients produced normal ocular VEMP (oVEMP). Caloric tests obtained normal results in all patients.

Frequency preference in cervical vestibular evoked myogenic potential of idiopathic otolithic vertigo patients. Does it reflect otolithic endolymphatic hydrops?

CONCLUSION: Idiopathic otolithic vertigo (IOV) with relatively long duration of attacks might be caused by endolymphatic hydrops in the otolith organ. OBJECTIVES: To clarify the pathophysiology underlying IOV, episodic tilting or translational sensation attacks by unknown causes, especially the possibility of endolymphatic hydrops in the otolith organ. METHODS: Sixteen patients (6 men and 10 women) diagnosed with having IOV were enrolled. In these subjects, frequency preference in cervical vestibular evoked myogenic potential (cVEMP) was studied. The subjects underwent cVEMP testing using 500 Hz and 1000 Hz short tone bursts (STB) (125 dB SPL, air-conducted sound). The 500-1000 Hz cVEMP slope was calculated and assessed in comparison with data from healthy subjects in the preceding study. RESULTS: Twelve of the 16 examined patients had a significant preference of 1000 Hz to 500 Hz, which was suggestive of endolymphatic hydrops in the saccule. Patients with frequency preference of 1000 Hz to 500 Hz showed a tendency for longer vertigo attacks than patients without preference of 1000 Hz.

Insulin-like growth factor 1 induces the transcription of Gap43 and Ntn1 during hair cell protection in the neonatal murine cochlea.

We previously reported that insulin-like growth factor 1 (IGF-1) protects cochlear hair cells against aminoglycosides through activation of the PI3K/Akt and MEK/ERK pathways in supporting cells. In this study, we found that IGF-1 up-regulated the expression levels of Gap43 and Ntn1 as measured using cDNA microarray analysis and qRT-PCR. Using inhibitors of the PI3K/Akt and MEK/ERK pathways, we reveal that both pathways are involved in the up-regulation of Gap43 and Ntn1 expression. Moreover the time window of Gap43 and Ntn1 transcription was limited to within 12h after IGF-1 treatment, indicating that downstream gene expression was tightly controlled by IGF-1.

Virus-induced expression of retinoic acid inducible gene-I and melanoma differentiation-associated gene 5 in the cochlear sensory epithelium.

The inner ear has been regarded as an immunoprivileged site because of isolation by the blood-labyrinthine barrier. Several reports have indicated the existence of immune cells in the inner ear, but there are no reports showing immunocompetence of the cochlear tissue. In this report, we examined the potential involvement of retinoic acid inducible gene-I (RIG-I) and melanoma differentiation-associated gene 5 (MDA5), which are critical for initiating antiviral innate immune responses. We found that RIG-I and MDA5 are expressed in the mouse cochlear sensory epithelium, including Hensen's and Claudius' cells. Ex vivo viral infection using Theiler's murine encephalomyelitis virus revealed that the virus replicates in these cells and that protein levels of RIG-I and MDA5 are up-regulated. Furthermore, the critical antiviral transcription factor, interferon (IFN) regulatory factor-3, is activated in the infected cells as judged by its nuclear translocation and the accumulation of type I IFN transcripts. These results strongly suggest that RIG-I and MDA5 participate in innate antiviral responses in cochlear tissue.

Insulin-like growth factor 1 inhibits hair cell apoptosis and promotes the cell cycle of supporting cells by activating different downstream cascades after pharmacological hair cell injury in neonatal mice.

Sensorineural hearing loss, which is mainly caused by cochlear hair cell damage, is an intractable disease, as cochlear hair cells and supporting cells are unable to proliferate in postnatal mammals. As a novel and potent treatment for sensorineural hearing loss, we have studied IGF-1 and found that it protects cochlear hair cells from the damage caused by noise and ischemic trauma. Through a clinical trial, we have also confirmed that IGF-1 is an effective treatment for idiopathic sudden sensorineural hearing loss. In the current study, we attempted to identify the downstream pathways of the IGF-1 signal and the mechanisms by which IGF-1 protects the neonatal mouse cochlear hair cells that have been damaged by neomycin. IGF-1 activated both the PI3K/Akt and MEK/ERK pathways to maintain the hair cell numbers in the injured cochlea. The PI3K/Akt pathway specifically protected the cochlear inner hair cells through the inhibition of apoptosis. In contrast, the MEK/ERK pathway induced the cell cycle promotion of Hensen's and Claudius' cells, the supporting cells that are located lateral to the outer hair cells of the cochlea. This cell cycle promotion of the supporting cells resulted in the maintenance of the outer hair cell numbers. These results indicate that IGF-1 is a growth factor that efficiently regulates different mechanisms through different downstream cascades, thereby protecting cochlear hair cells.

Insulin-like growth factor 1 protects vestibular hair cells from aminoglycosides.

This study investigated the therapeutic potential of insulin-like growth factor-1 (IGF-1) for vestibular hair cells using explant cultures of mouse utricles. After incubation with the ototoxic drug gentamicin, explants from neonatal mouse utricles were cultured in medium containing IGF-1 at various concentrations. Histological evaluation revealed significant increases in the number of surviving hair cells cultured with IGF-1 at concentrations reflecting a clinical setting. Immunostaining for trio-binding protein and espin showed the maintenance of functional structures in hair bundles at the apex of surviving hair cells. An FM1-43 assay indicated the presence of mechanoelectrical transduction channels in surviving hair cells. These findings indicate that IGF-1 may protect the functionality of vestibular hair cells against drug-induced injury.

[Case of frontal sinus carcinoma for which anterior skull base surgery was performed: application for resection of orbita].

Carcinoma of the nasal cavity and paranasal sinuses occupies only 3% of head and neck malignant tumors in the West, but 10% in Japan. Frontal sinus carcinoma is much rarer, occupying less than 1% of carcinoma of the nasal cavity and paranasal sinuses. In Japan, only 38 cases have been reported for 40 years, from 1924 to 1964. Almost all patients died within one year because only facial resection was performed. We report a case of frontal sinus carcinoma (squamous cell carcinoma) invasive the to skull base for which we performed anterior skull base surgery and can confirm two years survival in our institution. In this case, resection of the right orbit contents was performed, but careful consideration must be given to resection and repair of orbit contents for maintaining a patient's quality of life. Not only computed tomography scan and magnetic resonance imaging but also angiography is thought to be useful, especially for the ophthalmic artery (in this case, the lacrimal artery) is important.