AAV-Mediated Gene Therapy Restores Hearing in Patients with DFNB9 Deafness.

Mutations in OTOFERLIN (OTOF) lead to the autosomal recessive deafness 9 (DFNB9). The efficacy of adeno-associated virus (AAV)-mediated OTOF gene replacement therapy is extensively validated in Otof-deficient mice. However, the clinical safety and efficacy of AAV-OTOF is not reported. Here, AAV-OTOF is generated using good manufacturing practice and validated its efficacy and safety in mouse and non-human primates in order to determine the optimal injection dose, volume, and administration route for clinical trials. Subsequently, AAV-OTOF is delivered into one cochlea of a 5-year-old deaf patient and into the bilateral cochleae of an 8-year-old deaf patient with OTOF mutations. Obvious hearing improvement is detected by the auditory brainstem response (ABR) and the pure-tone audiometry (PTA) in these two patients. Hearing in the injected ear of the 5-year-old patient can be restored to the normal range at 1 month after AAV-OTOF injection, while the 8-year-old patient can hear the conversational sounds. Most importantly, the 5-year-old patient can hear and recognize speech only through the AAV-OTOF-injected ear. This study is the first to demonstrate the safety and efficacy of AAV-OTOF in patients, expands and optimizes current OTOF-related gene therapy and provides valuable information for further application of gene therapies for deafness.

Stem Cell-Based Therapies for Auditory Hair Cell Regeneration in the Treatment of Hearing Loss.

The incidence and prevalence of hearing loss is increasing globally at an accelerated pace. Hair cells represent the sensory receptors of auditory and vestibular systems. Hair cell absence, loss or degeneration due to congenital diseases, trauma, toxicity, infection or advancing age, results in disabling hearing loss. Regenerative medicine approaches consisting in stem cell-based hair cell rescue or regeneration, gene therapy, as well as cell and tissue engineering are expected to dramatically improve the therapeutic arsenal available for addressing hearing loss. Current strategies that are using different stem cell types to rescue or to induce hair cell proliferation and regeneration are presented. Gene and cell therapy methods that modulates transdifferentiation of surrounding cell types into hair cells are presented, together with their specific advantages and limitations. Several modalities for improving therapeutic targeting to the inner ear such as nanoparticle-mediated cell and gene delivery are introduced. Further steps in building more relevant high-throughput models for testing novel drugs and advanced therapies are proposed as a modality to accelerate translation to clinical settings.

Sordera infantil con discapacidad asociada (DA+): recomendaciones CODEPEH / Deaf children with additional disabilities (AD+): CODEPEH recommendations

Aproximadamente el 40% de los niños con sordera tienen añadido un trastorno del desarrollo o un problema médico importante, que puede retrasar la edad de diagnóstico de la hipoacusia y/o precisar de la intervención de otros profesionales. Esta situación se designa como «hipoacusia o sordera con discapacidad añadida» (DA+). El motivo por el que la población de niños con problemas auditivos es más propensa a asociar discapacidades añadidas radica en que los factores de riesgo para la hipoacusia se superponen con los de muchas otras discapacidades. Estos factores pueden influir en diversos aspectos del desarrollo, incluida la adquisición del lenguaje. Es importante comprobar que se recibe la adecuada atención, la efectividad de audífonos o implantes, así como de las estrategias de intervención logopédica, y la adherencia de la familia a sesiones y citas. Los desafíos que plantea la DA+ son su detección precoz, para permitir una temprana y adecuada intervención, y la necesidad de una colaboración transdisciplinar fluida entre todos los profesionales que han de intervenir, junto con la implicación de la familia. (AU)

Approximately 40% of children with deafness have an additional developmental disorder or major medical problem, which may delay the age of diagnosis of hearing loss and/or require intervention by other professionals. This situation is referred to as “deafness with added disability” (AD+). The reason why the population of hearing-impaired children is more likely to have associated added disabilities is that the risk factors for hearing impairment overlap with those for many other disabilities. These factors can influence various aspects of development, including language acquisition. It is important to check that appropriate care is received, the effectiveness of hearing aids or implants, as well speech therapy intervention strategies, and family adherence to sessions and appointments. The challenge posed by AD+ is early detection, to allow early and appropriate intervention, and the need for fluid transdisciplinary collaboration between all professionals involved, together with the involvement of the family. (AU)

Spread of activation and interaction between channels with multi-channel optogenetic stimulation in the mouse cochlea.

For individuals with severe to profound hearing loss resulting from irreversibly damaged hair cells, cochlear implants can be used to restore hearing by delivering electrical stimulation directly to the spiral ganglion neurons. However, current spread lowers the spatial resolution of neural activation. Since light can be easily confined, optogenetics is a technique that has the potential to improve the precision of neural activation, whereby visible light is used to stimulate neurons that are modified with light-sensitive opsins. This study compares the spread of neural activity across the inferior colliculus of the auditory midbrain during electrical and optical stimulation in the cochlea of acutely deafened mice with opsin-modified spiral ganglion neurons (H134R variant of the channelrhodopsin-2). Monopolar electrical stimulation was delivered via each of four 0.2 mm wide platinum electrode rings at 0.6 mm centre-to-centre spacing, whereas 453 nm wavelength light was delivered via each of five 0.22 × 0.27 mm micro-light emitting diodes (LEDs) at 0.52 mm centre-to-centre spacing. Channel interactions were also quantified by threshold changes during simultaneous stimulation by pairs of electrodes or micro-LEDs at different distances between the electrodes (0.6, 1.2 and 1.8 mm) or micro-LEDs (0.52, 1.04, 1.56 and 2.08 mm). The spread of activation resulting from single channel optical stimulation was approximately half that of monopolar electrical stimulation as measured at two levels of discrimination above threshold (p<0.001), whereas there was no significant difference between optical stimulation in opsin-modified deafened mice and pure tone acoustic stimulation in normal-hearing mice. During simultaneous micro-LED stimulation, there were minimal channel interactions for all micro-LED spacings tested. For neighbouring micro-LEDs/electrodes, the relative influence on threshold was 13-fold less for optical stimulation compared electrical stimulation (p<0.05). The outcomes of this study show that the higher spatial precision of optogenetic stimulation results in reduced channel interaction compared to electrical stimulation, which could increase the number of independent channels in a cochlear implant. Increased spatial resolution and the ability to activate more than one channel simultaneously could lead to better speech perception in cochlear implant recipients.

Indications of Effective Hyperbaric Oxygen Therapy Combined With Steroid Therapy for Sudden Hearing Loss.

OBJECTIVE: This study evaluated the therapeutic effect of hyperbaric oxygen therapy (HBOT) combined with steroid therapy to treat sudden hearing loss and examined the index associated with excellent therapeutic effect. METHODS: We included 109 patients with sudden hearing loss. Patients were divided into the HBOT combination group (59 sides) treated with HBOT and steroid therapy and HBOT noncombination group (50 sides) involving steroid therapy only. The recovery rate of each group was compared according to the severity of hearing loss. Blood samples were evaluated and inflammatory markers, such as neutrophil-lymphocyte ratio (NLR) and platelet-lymphocyte ratio (PLR), were calculated and compared by severity. We evaluated the usefulness of inflammatory markers for predicting recovery rate, and calculated cutoff values were also evaluated. RESULTS: The HBOT combination group exhibited a higher overall recovery rate than the HBOT noncombination group, particularly in severe cases. However, there was no significant difference in the severity of hearing loss based on various inflammatory markers. NLR and PLR are useful for predicting the effect in patients treated with concomitant HBOT. By setting 2.43 and 146.67 as cutoff values for NLR and PLR, respectively, we observed that lower values resulted in better recovery rates. CONCLUSION: The use of HBOT is effective for severe cases and early blood flow disorders with low NLR and PLR and less inflammation. When determining treatment, not only should the severity of hearing loss be considered, but also the NLR and PLR should be evaluated and examined based on the cutoff values.

The Opportunities and Challenges of Gene Therapy for Treatment of Inherited Forms of Vision and Hearing Loss.

Inherited forms of blindness and deafness are highly prevalent and severe conditions that significantly impact the lives of millions of people worldwide. The lack of therapeutic options for these conditions poses a major socioeconomic burden. Over the last decades, gene therapy has proven to be a life changing treatment for hereditary and acquired forms of diseases, and extensive preclinical investigation in animal models of both retinal and inner ear disorders has highlighted promising translational opportunities for these disorders too. This led to dozens of clinical trials investigating the efficiency of gene therapy-based approaches, with some of the products for retinal conditions successfully reaching phase III of development or even market authorization. However, challenges remain for the use of gene therapy, which are related to both the features of the delivery vehicles currently available and characteristics of the retinal and inner ear disorders targeted. Therefore, further developments in gene therapy platforms' design, including exploitation of novel technologies such as genome editing, RNA-targeted therapies, and optogenetics, are actively ongoing, driving the field forward. In this study, we review the ongoing applications and achievements of gene therapy for treatment of inherited forms of blindness and deafness as well as the developments that are being pursued in the field to overcome the current limitations.

Combined AAV-mediated gene replacement therapy improves auditory function in a mouse model of human DFNB42 deafness.

Hearing loss is a common disorder affecting nearly 20% of the world's population. Recently, studies have shown that inner ear gene therapy can improve auditory function in several mouse models of hereditary hearing loss. In most of these studies, the underlying mutations affect only a small number of cell types of the inner ear (e.g., sensory hair cells). Here, we applied inner ear gene therapy to the Ildr1Gt(D178D03)Wrst (Ildr1w-/-) mouse, a model of human DFNB42, non-syndromic autosomal recessive hereditary hearing loss associated with ILDR1 variants. ILDR1 is an integral protein of the tricellular tight junction complex and is expressed by diverse inner ear cell types in the organ of Corti and the cochlear lateral wall. We simultaneously applied two synthetic adeno-associated viruses (AAVs) with different tropism to deliver Ildr1 cDNA to the Ildr1w-/- mouse inner ear: one targeting the organ of Corti (AAV2.7m8) and the other targeting the cochlear lateral wall (AAV8BP2). We showed that combined AAV2.7m8/AAV8BP2 gene therapy improves cochlear structural integrity and auditory function in Ildr1w-/- mice.

Development and evaluation of helper dependent adenoviral vectors for inner ear gene delivery.

Viral vector gene therapy is an attractive strategy to treat hearing loss. Since hearing loss is due to a variety of pathogenic signaling cascades in distinct cells, viral vectors that can express large or multiple genes in a cell-type specific manner are needed. Helper-dependent adenoviral vectors (HdAd) are safe viral vectors with a large packaging capacity (-36 kb). Despite the potential of HdAd, its use in the inner ear is largely unexplored. Therefore, to evaluate the utility of HdAd for inner ear gene therapy, we created two HdAd vectors that use distinct cellular receptors for transduction: HdAd Serotype Type 5 (HdAd5), the Coxsackie-Adenovirus Receptor (CAR) and a chimeric HdAd 5/35, the human CD46+ receptor (hCD46). We delivered these vectors through the round window (RW) or scala media in CBA/J, C57Bl6/J and hCD46 transgenic mice. Immunostaining in conjunction with confocal microscopy of cochlear sections revealed that multiple cell types were transduced using HdAd5 and HdAd 5/35 in all mouse models. Delivery of HdAd5 via RW in the C57Bl/6 J or CBA/J cochlea resulted in transduced mesenchymal cells of the peri­lymphatic lining and modiolar region while scala media delivery resulted in transduction of supporting cells and inner hair cells. Hd5/35 transduction was CD46 dependent and RW delivery of HdAd5/35 in the hCD46 mouse model resulted in a similar transduction pattern as HdAd5 in the peri­lymphatic lining and modiolar region in the cochlea. Our data indicate that HdAd vectors are promising vectors for use in inner ear gene therapy to treat some causes of hearing loss.

Deafness: from genetic architecture to gene therapy.

Progress in deciphering the genetic architecture of human sensorineural hearing impairment (SNHI) or loss, and multidisciplinary studies of mouse models, have led to the elucidation of the molecular mechanisms underlying auditory system function, primarily in the cochlea, the mammalian hearing organ. These studies have provided unparalleled insights into the pathophysiological processes involved in SNHI, paving the way for the development of inner-ear gene therapy based on gene replacement, gene augmentation or gene editing. The application of these approaches in preclinical studies over the past decade has highlighted key translational opportunities and challenges for achieving effective, safe and sustained inner-ear gene therapy to prevent or cure monogenic forms of SNHI and associated balance disorders.

Rescue of auditory function by a single administration of AAV-TMPRSS3 gene therapy in aged mice of human recessive deafness DFNB8.

Patients with mutations in the TMPRSS3 gene suffer from recessive deafness DFNB8/DFNB10. For these patients, cochlear implantation is the only treatment option. Poor cochlear implantation outcomes are seen in some patients. To develop biological treatment for TMPRSS3 patients, we generated a knockin mouse model with a frequent human DFNB8 TMPRSS3 mutation. The Tmprss3A306T/A306T homozygous mice display delayed onset progressive hearing loss similar to human DFNB8 patients. Using AAV2 as a vector to carry a human TMPRSS3 gene, AAV2-hTMPRSS3 injection in the adult knockin mouse inner ear results in TMPRSS3 expression in the hair cells and the spiral ganglion neurons. A single AAV2-hTMPRSS3 injection in Tmprss3A306T/A306T mice of an average age of 18.5 months leads to sustained rescue of the auditory function to a level similar to wild-type mice. AAV2-hTMPRSS3 delivery rescues the hair cells and the spiral ganglions neurons. This study demonstrates successful gene therapy in an aged mouse model of human genetic deafness. It lays the foundation to develop AAV2-hTMPRSS3 gene therapy to treat DFNB8 patients, as a standalone therapy or in combination with cochlear implantation.

Longitudinal Changes in BDNF and MMP-9 Protein Plasma Levels in Children after Cochlear Implantation.

Congenitally deaf children who undergo cochlear implantation before 1 year of age develop their auditory skills faster than children who are implanted later. In this longitudinal study, a cohort of 59 implanted children were divided into two subgroups according to their ages at implantation-below or above 1 year old-and the plasma levels of matrix metalloproteinase-9 (MMP-9), brain-derived neurotrophic factor (BDNF), and pro-BDNF were measured at 0, 8, and 18 months after cochlear implant activation, while auditory development was simultaneously evaluated using the LittlEARs Questionnaire (LEAQ). A control group consisted of 49 age-matched healthy children. We identified statistically higher BDNF levels at 0 months and at the 18-month follow-ups in the younger subgroup compared to the older one and lower LEAQ scores at 0 months in the younger subgroup. Between the subgroups, there were significant differences in the changes in BDNF levels from 0 to 8 months and in LEAQ scores from 0 to 18 months. The MMP-9 levels significantly decreased from 0 to 18 months and from 0 to 8 months in both subgroups and from 8 to 18 months only in the older one. For all measured protein concentrations, significant differences were identified between the older study subgroup and the age-matched control group.

Cochlear Health and Cochlear-implant Function.

The cochlear implant (CI) is widely considered to be one of the most innovative and successful neuroprosthetic treatments developed to date. Although outcomes vary, CIs are able to effectively improve hearing in nearly all recipients and can substantially improve speech understanding and quality of life for patients with significant hearing loss. A wealth of research has focused on underlying factors that contribute to success with a CI, and recent evidence suggests that the overall health of the cochlea could potentially play a larger role than previously recognized. This article defines and reviews attributes of cochlear health and describes procedures to evaluate cochlear health in humans and animal models in order to examine the effects of cochlear health on performance with a CI. Lastly, we describe how future biologic approaches can be used to preserve and/or enhance cochlear health in order to maximize performance for individual CI recipients.

Locus coeruleus activity improves cochlear implant performance.

Cochlear implants (CIs) are neuroprosthetic devices that can provide hearing to deaf people1. Despite the benefits offered by CIs, the time taken for hearing to be restored and perceptual accuracy after long-term CI use remain highly variable2,3. CI use is believed to require neuroplasticity in the central auditory system, and differential engagement of neuroplastic mechanisms might contribute to the variability in outcomes4-7. Despite extensive studies on how CIs activate the auditory system4,8-12, the understanding of CI-related neuroplasticity remains limited. One potent factor enabling plasticity is the neuromodulator noradrenaline from the brainstem locus coeruleus (LC). Here we examine behavioural responses and neural activity in LC and auditory cortex of deafened rats fitted with multi-channel CIs. The rats were trained on a reward-based auditory task, and showed considerable individual differences of learning rates and maximum performance. LC photometry predicted when CI subjects began responding to sounds and longer-term perceptual accuracy. Optogenetic LC stimulation produced faster learning and higher long-term accuracy. Auditory cortical responses to CI stimulation reflected behavioural performance, with enhanced responses to rewarded stimuli and decreased distinction between unrewarded stimuli. Adequate engagement of central neuromodulatory systems is thus a potential clinically relevant target for optimizing neuroprosthetic device use.

Usos de cámara hiperbárica en otorrinolaringología / Uses for hyperbaric chambers in otolaryngology

Resumen En la terapia con oxígeno hiperbárico (HBO) se utiliza oxígeno al 100% de concentración en una cámara presurizada con presiones supraatmosféricas, que corresponden de 2 a 3 atmósferas. Los mecanismos por los cuales funciona esta terapia se relacionan con propiedades físicas de los gases y su comportamiento fisiológico en el organismo, lo que lleva finalmente a la hiperoxia, evento fisiológico que permite la obtención de diversos efectos beneficiosos. La evidencia en medicina ha demostrado su utilidad mayormente en la enfermedad por descompresión, infecciones cutáneas graves e intoxicación por monóxido de carbono. En el ámbito de la otorrinolaringología ha probado ser útil en algunas enfermedades como la hipoacusia súbita idiopática, tanto como terapia única como asociada al uso de corticosteroides, como en la osteomielitis refractaria del oído externo, la que en conjunto con antibioticoterapia y manejo quirúrgico presenta un evidente aumento en la tasa de mejoría. Cabe mencionar que la terapia con HBO ha demostrado también beneficios en los tratamientos y complicaciones posteriores a la radiación en pacientes con cáncer de cabeza y cuello. Es importante mencionar que la terapia con HBO no está exenta de riesgos y requiere que los pacientes cumplan con características específicas para su utilización, por lo que su indicación debe ser juiciosa y en casos seleccionados.

Abstract In hyperbaric oxygen therapy, 100% pure oxygen is used in a pressurized chamber with super atmospheric pressures which correspond to 2-3 atmospheres. The mechanism by which this treatment works is related to the physical properties of gases and their physiological behavior in the body, which leads to hyperoxia, the physiological event which allows for diverse beneficial health effects. The evidence in medicine has proven its utility mainly in decompression sickness, severe skin infections and carbon monoxide poisoning. In the otolaryngology field it has been proven useful in diseases like idiopathic sudden sensorineural hearing loss, both as the only treatment and as a concurrent treatment along with corticosteroids, in malignant otitis externa which in conjunction with antibiotic treatment and a surgical approach presents a clear increase in improvement rates. It must be mentioned that hyperbaric chamber treatment has also shown benefits in radiation treatment and post radiation complications in head and neck cancer patients. It is important to note that hyperbaric oxygen therapy is not without risks and patients must meet specific criteria for it to be applied, therefore it must be indicated using careful judgement and only in necessary cases.

The Genomics of Auditory Function and Disease.

Current estimates suggest that nearly half a billion people worldwide are affected by hearing loss. Because of the major psychological, social, economic, and health ramifications, considerable efforts have been invested in identifying the genes and molecular pathways involved in hearing loss, whether genetic or environmental, to promote prevention, improve rehabilitation, and develop therapeutics. Genomic sequencing technologies have led to the discovery of genes associated with hearing loss. Studies of the transcriptome and epigenome of the inner ear have characterized key regulators and pathways involved in the development of the inner ear and have paved the way for their use in regenerative medicine. In parallel, the immense preclinical success of using viral vectors for gene delivery in animal models of hearing loss has motivated the industry to work on translating such approaches into the clinic. Here, we review the recent advances in the genomics of auditory function and dysfunction, from patient diagnostics to epigenetics and gene therapy.

AAV-ie-K558R mediated cochlear gene therapy and hair cell regeneration.

The cochlea consists of multiple types of cells, including hair cells, supporting cells and spiral ganglion neurons, and is responsible for converting mechanical forces into electric signals that enable hearing. Genetic and environmental factors can result in dysfunctions of cochlear and auditory systems. In recent years, gene therapy has emerged as a promising treatment in animal deafness models. One major challenge of the gene therapy for deafness is to effectively deliver genes to specific cells of cochleae. Here, we screened and identified an AAV-ie mutant, AAV-ie-K558R, that transduces hair cells and supporting cells in the cochleae of neonatal mice with high efficiency. AAV-ie-K558R is a safe vector with no obvious deficits in the hearing system. We found that AAV-ie-K558R can partially restore the hearing loss in Prestin KO mice and, importantly, deliver Atoh1 into cochlear supporting cells to generate hair cell-like cells. Our results demonstrate the clinical potential of AAV-ie-K558R for treating the hearing loss caused by hair cell death.

Barriers to Receiving Necessary Hearing Care Among US Children.

OBJECTIVE: We aim to clarify the national scope of unmet pediatric hearing care needs and identify specific barriers to hearing care. STUDY DESIGN: Cross-sectional study of a nationally representative data set. SETTING: This study is based on the combined 2016 and 2017 National Survey of Children's Health. This survey covers the physical and emotional health, access to care, and social context of US children and adolescents aged 0 to 17 years. METHODS: Analysis of parent-reported responses of children's hearing status, access to care, and perceived barriers. RESULTS: Overall, 0.3% (n = 206,200) of US children surveyed reported needing hearing care, which was not received. A further 1.3% (n = 934,000) reported deafness or problems with hearing, and of these, 6.4% (n = 60,000) reported not receiving necessary hearing care. Rates of insurance coverage between children with deafness/hearing problems and the general population were similar (91.7% vs 93.9%); however, deaf or hard-of-hearing children with unmet hearing care needs were more likely to be from non-White backgrounds (P = .009) and to lack health insurance coverage (P = .001). Rates of unfulfilled hearing care by reason were as follows: 57.5% without eligibility for the service, 45.4% reporting the service was not available in their area, 53.7% with difficulty obtaining an appointment, and 53.5% reporting issues with cost. CONCLUSION: Over 200,000 children annually do not receive necessary hearing-related care despite high rates of insurance coverage, and nearly 60,000 of these children are deaf or hard of hearing. Cost, eligibility for and distribution of services, and timely appointments are the primary barriers to hearing health care.