Sensorineural hearing loss (SNHL), the most commonly-occurring form of hearing loss, is caused mainly by injury to or the loss of hair cells and spiral ganglion neurons in the cochlea. Numerous environmental and physiological factors have been shown to cause acquired SNHL, such as ototoxic drugs, noise exposure, aging, infections, and diseases. Several programmed cell death (PCD) pathways have been reported to be involved in SNHL, especially some novel PCD pathways that have only recently been reported, such as ferroptosis, necroptosis, and pyroptosis. Here we summarize these PCD pathways and their roles and mechanisms in SNHL, aiming to provide new insights and potential therapeutic strategies for SNHL by targeting these PCD pathways.
Humans ; Hearing Loss, Sensorineural/metabolism* ; Necroptosis/drug effects* ; Pyroptosis/drug effects* ; Ferroptosis/drug effects* ; Animals

OBJECTIVE: To explore the clinical phenotype and genetic features of two children with MEGDEL syndrome due to variants of the SERAC1 gene. METHODS: Two children who had presented at the Fujian Medical University Union Hospital respectively on July 14, 2020 and July 28, 2018 were selected as the study subjects. Clinical features and results of genetic testing were retrospectively analyzed. RESULTS: Both children had featured developmental delay, dystonia and sensorineural deafness, along with increased urine 3-methylglutaric acid levels. Magnetic resonance imaging revealed changes similar to Leigh-like syndrome. Gene sequencing revealed that both children have harbored pathogenic compound heterozygous variants of the SERAC1 gene, including c.1159C>T and c.442C>T in child 1, and c.1168C>T and exons 4~9 deletion in child 2. CONCLUSION Children with MEGDEL syndrome due to SERAC1 gene variants have variable clinical genotypes. Delineation of its clinical characteristics and typical imaging changes can facilitate early diagnosis and treatment. Discovery of the novel variants has also enriched the spectrum of SERAC1 gene variants.
Humans ; Retrospective Studies ; Metabolism, Inborn Errors ; Hearing Loss, Sensorineural/genetics* ; Dystonia ; Carboxylic Ester Hydrolases

OBJECTIVE: To explore the clinical and genetic characteristics of a child with MEGDEL syndrome. METHODS: Clinical data of the child was reviewed. Peripheral blood samples of the child and his parents were collected. Mitochondrial genome and the whole exome of the child were analyzed by next-generation sequencing. Candidate variants and its origin were verified by Sanger sequencing and fluorescence quantitative PCR. RESULTS: The patient, a 2-year-and-6-month-old male, has featured hypoglycemia, mental and motor retardation with regression. Cranial MRI showed bilateral putamen damage suggestive of Leigh syndrome. Testing of urine organic acid indicated that the level of 3-methylpentenoic acid was slightly increased. Whole exome sequencing revealed that the child has harbored heterozygous deletion of exons 6 to 17 and c.307A>T nonsense variant of the SERAC1 gene, which were respectively inherited from his parents who were asymptomatic. Treatment with Levocarnitine, vitamin B1, vitamin B2, coenzyme Q10, baclofen and glucuronolactone resulted in improvement of sleep and mental state. CONCLUSION A case of MEGDEL syndrome without deafness was diagnosed. Discovery of the nonsense mutation and large fragment deletion have enriched the spectrum of SERAC1 gene variants.
Child, Preschool ; Hearing Loss, Sensorineural/genetics* ; Humans ; Leigh Disease ; Male ; Metabolism, Inborn Errors/genetics* ; Molecular Biology ; Mutation

Objective: Hyperbaric oxygen treatment (HBOT) has demonstrated efficacy in improving hearing levels of patients with idiopathic sudden sensorineural hearing loss (ISSHL); however, the underlying mechanisms are not well understood. HBOT alleviates the inflammatory response, which is mediated by Toll-like receptor (TLR) 4 and nuclear factor (NF)-κB. In this study we investigated whether HBOT attenuates inflammation in ISHHL patients alteration of TLR4 and NF-κB expression. Methods: ISHHL patients ( = 120) and healthy control subjects ( = 20) were enrolled in this study. Patients were randomly divided into medicine group treated with medicine only ( = 60) and HBO group receiving both HBOT and medicine ( = 60). Audiometric testing was performed pre- and post-treatment. TLR4, NF-кB, and TNF-α expression in peripheral blood of ISSHL patients and healthy control subjects was assessed by ELISA before and after treatment. Results: TLR4, NF-κB, and TNF-α levels were upregulated in ISSHL patients relative to healthy control subjects; the levels were decreased following treatment and were lower in the HBO group than that in the medicine group post-treatment ( < 0.05 and < 0.01). Conclusion HBOT alleviates hearing loss in ISSHL patients by suppressing the inflammatory response induced by TLR4 and NF-κB signaling.
Adolescent ; Adult ; Aged ; China ; Female ; Hearing Loss, Sensorineural ; therapy ; Hearing Loss, Sudden ; therapy ; Humans ; Hyperbaric Oxygenation ; Inflammation ; genetics ; therapy ; Male ; Middle Aged ; NF-kappa B p50 Subunit ; genetics ; metabolism ; Toll-Like Receptor 4 ; genetics ; metabolism ; Young Adult

Hearing loss is the most frequent sensorineural disorder worldwild, among which about 50% are caused by genetic factors. TMC1 is one of the common genes causing hereditary hearing loss. TMC1 mutations can cause pre-lingual profound/severe autosomal recessive (DFNB7/11) and post-lingual progressive autosomal dominant (DFNA36) non-syndromic hearing loss. Murine models studies show that TMC1, 2 are expressed in cochlea inner and outer hair cells and maintain normal mechanoelectrical transduction (MET) functions of the hair cells. A growing number of evidence indicate that TMC1, 2 are components of the MET complex. It is necessary to definite the precise distribution and exact function of TMC1, 2, because it is important to understand the regulating mechanism of auditory function.
Animals ; Cochlea ; metabolism ; Disease Models, Animal ; Hair Cells, Auditory, Outer ; metabolism ; Hearing Loss, Sensorineural ; genetics ; Humans ; Membrane Proteins ; genetics ; Mice ; Mutation

Previously, we reported the expression levels of specific microRNA machinery components, DGCR8 and AGO2, and their clinical association in patients with idiopathic sudden hearing loss (SSNHL). In the present study, we investigated the other important components of microRNA machinery and their association with clinical parameters in SSNHL patients. Fifty-seven patients diagnosed with SSNHL and fifty healthy volunteers were included in this study. We evaluated mRNA expression levels of Dicer and Drosha in whole blood of patients with SSNHL and the control group, using RT & real-time PCR analysis. The Dicer mRNA expression level was down-regulated in patients with SSNHL. However, the Drosha mRNA expression level was not significantly altered in patients with SSNHL. Neither the Dicer nor Drosha mRNA expression level was not associated with any clinical parameters, including age, sex, duration of initial treatment from onset (days), initial Pure tone average, Siegel's criteria, WBC, and Erythrocyte sedimentation rate. However, mRNA expression levels of Dicer and Drosha were positively correlated to each other in patients with SSNHL. In this study, we demonstrated for the first time that the Dicer mRNA expression level was down-regulated in patients with SSNHL, suggesting its important role in pathobiology of SSNHL development.
Acute Disease ; Adult ; Biomarkers ; DEAD-box RNA Helicases/*blood ; Down-Regulation ; Female ; Gene Expression Regulation ; Hearing Loss, Sensorineural/*blood ; Hearing Loss, Sudden/*blood ; Humans ; Male ; MicroRNAs/*metabolism ; Middle Aged ; Ribonuclease III/*blood/*metabolism ; Statistics as Topic

Inwardly rectifying potassium (Kir) channels exhibit an asymmetrical conductance at hyperpolarization (high conductance) compared to depolarization (low conductance). The KCNJ10 gene which encodes an inwardly rectifying K+ channel Kir4.1 subunit plays an essential role in the inner ear and hearing. Mutations or deficiency of KCNJ10 can cause hearing loss with epilepsy, ataxia, sensorineural deafness, and renal tubulopathy (EAST) or SeSAME (seizures, sensorineural deafness, ataxia, mental retardation, and electrolyte imbalance) syndromes. In this review, we mainly focus on the expression and function of Kir4.1 channels in the inner ear and mutation-induced EAST/SeSAME syndromes to provide insight for understanding the pathogenesis of deafness induced by KCNJ10 deficiency.
Deafness ; genetics ; metabolism ; Ear, Inner ; metabolism ; Hearing Loss, Sensorineural ; genetics ; metabolism ; Humans ; Intellectual Disability ; genetics ; metabolism ; Mutation ; Potassium Channels, Inwardly Rectifying ; genetics ; metabolism ; Seizures ; genetics ; metabolism

INTRODUCTIONSensori-neural hearing loss (SNHL) is a frequent complication of conventional radiotherapy for head and neck tumours, especially nasopharyngeal carcinoma. To manage radiation-induced ototoxicity appropriately, an understanding of the cellular and molecular basis of this complication is necessary.

MATERIALS AND METHODSA medline search of relevant literature was done, focusing on the radiation-induced cellular and molecular processes that lead to hair cell death in the cochlea.

RESULTSRadiation-induced SNHL occurs in the cochlea, with the retro-cochlear pathways remaining functionally intact. By simulating radiotherapy regimes used clinically, radiation-induced cochlear cell degeneration in the absence of damage to the supporting structures and blood vessels has been demonstrated in animals. This could be due to apoptotic cochlear cell death, which has been shown to be associated with p53 upregulation and intra-cellular reactive oxygen species (ROS) generation. Oxidative stress may initiate the upstream processes that lead to apoptosis and other cell death mechanisms.

CONCLUSIONSA model of radiation-induced SNHL based on a dose and ROS-dependent cochlear cell apoptosis, is proposed. This model supports the feasibility of cochlear implantation, should one be clinically indicated. It can explain clinical observations such as radiation-induced SNHL being dose-dependent and affects the high frequencies more than the lower frequencies. It also opens up the possibility of preventive strategies targeted at different stages of the apoptotic process. Antioxidants look promising as effective agents to prevent radiation-induced ototoxicity; they target upstream processes leading to different cell death mechanisms that may co-exist in the population of damaged cells.

Animals ; Cell Death ; Cell Line ; Cochlea ; radiation effects ; Genes, p53 ; Hair Cells, Auditory ; radiation effects ; Hearing Loss, Sensorineural ; etiology ; genetics ; physiopathology ; Humans ; Mice ; Radiation Injuries ; complications ; Reactive Oxygen Species ; metabolism

AIMTo study the expression of iNOS and AChE on ginea pigs cochlea spiral ganglion induced by streptomycin (SM) and attenuation by salvia miltiorrhiza injection (Chinese Traditional medicine-dansen DS).

METHODS32 guinea pigs were divided into 4 groups randomly (n=8): control group, SM group, DS + SM group, DS group. SABC immunohistochemical staining and image quantitative analysis technique were used to observe the expression of iNOS and AChE, as well as grey value analysis, and ABR measurements were used to observe ototoxicity.

RESULTSAfter 10 days with drugs, the ABR threshold value of SM increased more significantly than that of the control (P < 0.01), while the ABR threshold value of DS+ SM co-treatment increased than the control group, but lower than that of SM group (P < 0.01). The results of immunohistochemical staining implied the expression of iNOS and AChE in SG of SM group were higher than that of control group, and had positive correlate.

CONCLUSIONThe ABR threshold value increases and the expression of iNOS and AChE strengthen on SM ototoxicity, and has some correlation. DS can attenuate the ototoxicity induced by SM, and has protective function.

Acetylcholinesterase ; metabolism ; Animals ; Cochlea ; drug effects ; metabolism ; Drugs, Chinese Herbal ; pharmacology ; Female ; Guinea Pigs ; Hearing Loss, Sensorineural ; chemically induced ; pathology ; prevention & control ; Male ; Nitric Oxide Synthase Type II ; metabolism ; Protective Agents ; pharmacology ; Random Allocation ; Salvia miltiorrhiza ; chemistry ; Spiral Ganglion ; drug effects ; metabolism ; Streptomycin ; toxicity

OBJECTIVETo study the effect of Gushen Peiyuan Recipe (GPR) on the expression of Bcl-2 and Bax mRNA in Shen-yang-deficiency (SYD) rats suffering from cochlea apoptosis, thus providing a theoretical basis to the treatment and prevention of sensorineural hearing loss and fill Chinese medine's theory of kidney-ear-correlation with new substance.

METHODSRats were induced into experimental SYD animal models by injecting cetacort into their buttocks. Rats in the blank and model groups were given 10 mL/kg normal saline by gastrogavage, and 31 g/kg, 15.5 g/kg and 7.5 g/kg GPR were given to the rats in the high, medium and low dose groups by gastrogavage respectively. RT-PCR was adopted to detect the mRNA expressions of Bcl-2 and Bax.

RESULTSLevels of Bcl-2 mRNA expression and Bcl-2/Bax enhanced, and mRNA expression of Bax attenuated in the model rats after GPR treatment, the Bcl-2/Bax ratio increased, showing insignificant difference when compared with the blank control group (P > 0.05).

CONCLUSIONGPR plays a significant role in regulating the mRNA expressions of Bcl-2 and Bax, therefore improving the hearing of SYD rats and protecting the structure and function of cochlea.

Animals ; Cochlea ; metabolism ; Diagnosis, Differential ; Drugs, Chinese Herbal ; therapeutic use ; Hearing Loss, Sensorineural ; drug therapy ; metabolism ; Kidney Diseases ; drug therapy ; metabolism ; Male ; Medicine, Chinese Traditional ; Phytotherapy ; Proto-Oncogene Proteins c-bcl-2 ; genetics ; metabolism ; RNA, Messenger ; genetics ; metabolism ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Yang Deficiency ; drug therapy ; metabolism ; bcl-2-Associated X Protein ; genetics ; metabolism