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Wang L, Zhang R, Jiang L, Gao S, Wu J, Jiao Y. Biomaterials as a new option for treating sensorineural hearing loss. Biomater Sci 2024; 12:4006-4023. [PMID: 38979939 DOI: 10.1039/d4bm00518j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/10/2024]
Abstract
Sensorineural hearing loss (SNHL) usually involves damage to complex auditory pathways such as inner ear cells and auditory nerves. The highly intricate and nuanced characteristics of these cells render their repair and regeneration extremely challenging, making it difficult to restore hearing to normal levels once it has been compromised. The effectiveness of traditional drugs is so minimal that they provide little help with the treatment. Fortunately, extensive experiments have demonstrated that combining biomaterials with conventional techniques significantly enhances drug effectiveness. This article reviews the research progress of biomaterials in protecting hair cells and the auditory nerve, repairing genes related to hearing, and developing artificial cochlear materials. By organizing the knowledge presented in this article, perhaps new insights can be provided for the clinical management of SNHL.
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Affiliation(s)
- Liwen Wang
- Department of Otorhinolaryngology Head and Neck Surgery, Guangzhou Twelfth People's Hospital (The Affiliated Twelfth People's Hospital of Guangzhou Medical University), Guangzhou 510620, China
- Institute of Otorhinolaryngology, Head and Neck Surgery, Guangzhou Medical University, Guangzhou 510620, China.
| | - Ruhe Zhang
- Department of Hematology, The Seventh Affiliated Hospital, Sun Yat-sen University, Shenzhen 518107, China
| | - Linlan Jiang
- Department of Otorhinolaryngology Head and Neck Surgery, Guangzhou Twelfth People's Hospital (The Affiliated Twelfth People's Hospital of Guangzhou Medical University), Guangzhou 510620, China
- Institute of Otorhinolaryngology, Head and Neck Surgery, Guangzhou Medical University, Guangzhou 510620, China.
| | - Shuyi Gao
- Department of Otorhinolaryngology Head and Neck Surgery, Guangzhou Twelfth People's Hospital (The Affiliated Twelfth People's Hospital of Guangzhou Medical University), Guangzhou 510620, China
- Institute of Otorhinolaryngology, Head and Neck Surgery, Guangzhou Medical University, Guangzhou 510620, China.
| | - Jun Wu
- Institute of Otorhinolaryngology, Head and Neck Surgery, Guangzhou Medical University, Guangzhou 510620, China.
- Bioscience and Biomedical Engineering Thrust, The Hong Kong University of Science and Technology (Guangzhou), Nansha, Guangzhou 511400, China.
- Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Yuenong Jiao
- Department of Otorhinolaryngology Head and Neck Surgery, Guangzhou Twelfth People's Hospital (The Affiliated Twelfth People's Hospital of Guangzhou Medical University), Guangzhou 510620, China
- Institute of Otorhinolaryngology, Head and Neck Surgery, Guangzhou Medical University, Guangzhou 510620, China.
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Altay DU, Korkmaz H, Korkmaz M, Noyan T. Relationship Between Serum Brain-Derived Neurotrophic Factor and Neurotrophin-3 Levels and Hearing Thresholds in Patients With Age-Related Hearing Loss. JOURNAL OF SPEECH, LANGUAGE, AND HEARING RESEARCH : JSLHR 2024; 67:1976-1983. [PMID: 38687186 DOI: 10.1044/2024_jslhr-23-00440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2024]
Abstract
BACKGROUND Age-related hearing loss (ARHL) is a general term used to describe the sensorineural type of hearing loss occurring in both ears in older adults. Neurotrophins are the most promising candidates for supporting the auditory nerve by increasing neuronal survival. This study aimed to help elucidate the pathophysiology of ARHL by determining whether any relationship exists between brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) levels in serum samples from patients diagnosed with ARHL. MATERIALS AND METHOD Seventy-seven individuals, a study group of 41 patients diagnosed with ARHL, and a control group of 36 participants without hearing loss were evaluated. Serum samples were collected and used to measure serum BDNF and NT-3 levels with the new Nepenthe enzyme-linked immunosorbent assay method. RESULTS Median pure-tone average results in the 2000, 4000, and 6000 Hz ranges were 52.5 (44.3-67.3) dB HL in the ARHL group and 13.5 (11.1-17.1) dB HL in the control group. The difference was statistically significant (p = .001). Although NT-3 and BDNF levels were both lower in ARHL patients than in participants without hearing loss, only the BDNF levels were significantly (p = .002) lower. Mean left and right ear word recognition scores were also lower in ARHL patients than in control groups. The ARHL group was further divided into two subgroups based on word recognition scores to evaluate significant differences in BDNF and NT-3 levels. No statistically significant difference was observed in BDNF and NT-3 levels between these subgroups. However, there was a significant difference in word recognition scores. CONCLUSIONS Low BDNF levels in the ARHL group suggest that BDNF may play a role in the pathogenesis of ARHL. Patients with low (ARHL1) and high (ARHL2) word recognition scores were compared for the first time in the literature in terms of BDNF and NT-3 levels. However, the results were not statistically significant. This article is a preliminary study and was written to provide guidance for our next comprehensive project.
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Affiliation(s)
- Diler Us Altay
- Department of Nutrition and Dietetics, Faculty of Health Sciences, Ordu University, Turkey
| | - Hakan Korkmaz
- Department of Otorhinolaryngology, Faculty of Medicine, Ordu University, Turkey
| | - Mukadder Korkmaz
- Department of Otorhinolaryngology, Faculty of Medicine, Ordu University, Turkey
| | - Tevfik Noyan
- Department of Medical Biochemistry, Faculty of Medicine, Ordu University, Turkey
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Ji L, Borges BC, Martel DT, Wu C, Liberman MC, Shore SE, Corfas G. From hidden hearing loss to supranormal auditory processing by neurotrophin 3-mediated modulation of inner hair cell synapse density. PLoS Biol 2024; 22:e3002665. [PMID: 38935589 PMCID: PMC11210788 DOI: 10.1371/journal.pbio.3002665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Accepted: 05/07/2024] [Indexed: 06/29/2024] Open
Abstract
Loss of synapses between spiral ganglion neurons and inner hair cells (IHC synaptopathy) leads to an auditory neuropathy called hidden hearing loss (HHL) characterized by normal auditory thresholds but reduced amplitude of sound-evoked auditory potentials. It has been proposed that synaptopathy and HHL result in poor performance in challenging hearing tasks despite a normal audiogram. However, this has only been tested in animals after exposure to noise or ototoxic drugs, which can cause deficits beyond synaptopathy. Furthermore, the impact of supernumerary synapses on auditory processing has not been evaluated. Here, we studied mice in which IHC synapse counts were increased or decreased by altering neurotrophin 3 (Ntf3) expression in IHC supporting cells. As we previously showed, postnatal Ntf3 knockdown or overexpression reduces or increases, respectively, IHC synapse density and suprathreshold amplitude of sound-evoked auditory potentials without changing cochlear thresholds. We now show that IHC synapse density does not influence the magnitude of the acoustic startle reflex or its prepulse inhibition. In contrast, gap-prepulse inhibition, a behavioral test for auditory temporal processing, is reduced or enhanced according to Ntf3 expression levels. These results indicate that IHC synaptopathy causes temporal processing deficits predicted in HHL. Furthermore, the improvement in temporal acuity achieved by increasing Ntf3 expression and synapse density suggests a therapeutic strategy for improving hearing in noise for individuals with synaptopathy of various etiologies.
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Affiliation(s)
- Lingchao Ji
- Kresge Hearing Research Institute and Department of Otolaryngology—Head and Neck Surgery, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Beatriz C. Borges
- Kresge Hearing Research Institute and Department of Otolaryngology—Head and Neck Surgery, University of Michigan, Ann Arbor, Michigan, United States of America
| | - David T. Martel
- Kresge Hearing Research Institute and Department of Otolaryngology—Head and Neck Surgery, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Calvin Wu
- Kresge Hearing Research Institute and Department of Otolaryngology—Head and Neck Surgery, University of Michigan, Ann Arbor, Michigan, United States of America
| | - M. Charles Liberman
- Mass Eye and Ear Infirmary and Harvard Medical School. Boston, Massachusetts, United States of America
| | - Susan E. Shore
- Kresge Hearing Research Institute and Department of Otolaryngology—Head and Neck Surgery, University of Michigan, Ann Arbor, Michigan, United States of America
- Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, United States of America
- Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Gabriel Corfas
- Kresge Hearing Research Institute and Department of Otolaryngology—Head and Neck Surgery, University of Michigan, Ann Arbor, Michigan, United States of America
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Kim MJ, Simms S, Behnammanesh G, Honkura Y, Suzuki J, Park HJ, Milani M, Katori Y, Bird JE, Ikeda A, Someya S. A Mutation in Tmem135 Causes Progressive Sensorineural Hearing Loss. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.09.593414. [PMID: 38766120 PMCID: PMC11100813 DOI: 10.1101/2024.05.09.593414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Transmembrane protein 135 (TMEM135) is a 52 kDa protein with five predicted transmembrane domains that is highly conserved across species. Previous studies have shown that TMEM135 is involved in mitochondrial dynamics, thermogenesis, and lipid metabolism in multiple tissues; however, its role in the inner ear or the auditory system is unknown. We investigated the function of TMEM135 in hearing using wild-type (WT) and Tmem135 FUN025/FUN025 ( FUN025 ) mutant mice on a CBA/CaJ background, a normal-hearing mouse strain. Although FUN025 mice displayed normal auditory brainstem response (ABR) at 1 month, we observed significantly elevated ABR thresholds at 8, 16, and 64 kHz by 3 months, which progressed to profound hearing loss by 12 months. Consistent with our auditory testing, 13-month-old FUN025 mice exhibited a severe loss of outer hair cells and spiral ganglion neurons in the cochlea. Our results using BaseScope in situ hybridization indicate that TMEM135 is expressed in the inner hair cells, outer hair cells, and supporting cells. Together, these results demonstrate that the FUN025 mutation in Tmem135 causes progressive sensorineural hearing loss, and suggest that TMEM135 is crucial for maintaining key cochlear cell types and normal sensory function in the aging cochlea.
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Lee C, Hartsock JJ, Salt AN, Lichtenhan JT. A Guinea Pig Model Suggests That Objective Assessment of Acoustic Hearing Preservation in Human Ears With Cochlear Implants Is Confounded by Shifts in the Spatial Origin of Acoustically Evoked Potential Measurements Along the Cochlear Length. Ear Hear 2024; 45:666-678. [PMID: 38178312 DOI: 10.1097/aud.0000000000001457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2024]
Abstract
OBJECTIVES Our recent empirical findings have shown that the auditory nerve compound action potential (CAP) evoked by a low-level tone burst originates from a narrow cochlear region tuned to the tone burst frequency. At moderate to high sound levels, the origins shift to the most sensitive audiometric regions rather than the extended high-frequency regions of the cochlear base. This means that measurements evoked from extended high-frequency sound stimuli can shift toward the apex with increasing level. Here we translate this study to understand the spatial origin of acoustically evoked responses from ears that receive cochlear implants, an emerging area of research and clinical practice that is not completely understood. An essential step is to first understand the influence of the cochlear implant in otherwise naive ears. Our objective was to understand how function of the high-frequency cochlear base, which can be excited by the intense low-frequency sounds that are frequently used for objective intra- and postoperative monitoring, can be influenced by the presence of the cochlear implant. DESIGN We acoustically evoked responses and made measurements with an electrode placed near the guinea pig round window. The cochlear implant was not utilized for either electrical stimulation or recording purposes. With the cochlear implant in situ, CAPs were acoustically evoked from 2 to 16 kHz tone bursts of various levels while utilizing the slow perfusion of a kainic acid solution from the cochlear apex to the cochlear aqueduct in the base, which sequentially reduced neural responses from finely spaced cochlear frequency regions. This cochlear perfusion technique reveals the spatial origin of evoked potential measurements and provides insight on what influence the presence of an implant has on acoustical hearing. RESULTS Threshold measurements at 3 to 11 kHz were elevated by implantation. In an individual ear, thresholds were elevated and lowered as cochlear implant was respectively inserted and removed, indicative of "conductive hearing loss" induced by the implant. The maximum threshold elevation occurred at most sensitive region of the naive guinea pig ear (33.66 dB at 8 kHz), making 11 kHz the most sensitive region to acoustic sounds for guinea pig ears with cochlear implants. Conversely, the acute implantation did not affect the low-frequency, 500 Hz thresholds and suprathreshold function, as shown by the auditory nerve overlapped waveform. As the sound pressure level of the tone bursts increased, mean data show that the spatial origin of CAPs along the cochlear length shifted toward the most sensitive cochlear region of implanted ears, not the extended high-frequency cochlear regions. However, data from individual ears showed that after implantation, measurements from moderate to high sound pressure levels originate in places that are unique to each ear. CONCLUSIONS Alterations to function of the cochlear base from the in situ cochlear implant may influence objective measurements of implanted ears that are frequently made with intense low-frequency sound stimuli. Our results from guinea pigs advance the interpretation of measurements used to understand how and when residual acoustic hearing is lost in human ears receiving a cochlear implant.
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Affiliation(s)
- Choongheon Lee
- Department of Otolaryngology, University of Rochester, Rochester, New York, USA
| | - Jared J Hartsock
- Department of Cochlear Surgery, Turner Scientific, Inc., Jacksonville, Illinois, USA
| | - Alec N Salt
- Department of Pharmacokinetics, Turner Scientific, Inc., Jacksonville, Illinois, USA
| | - Jeffery T Lichtenhan
- Department of Otolaryngology, University of South Florida Morsani School of Medicine, Tampa, Florida, USA
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Hemachandran S, Hu N, Kane CJ, Green SH. Cyclic AMP signaling promotes regeneration of cochlear synapses after excitotoxic or noise trauma. Front Cell Neurosci 2024; 18:1363219. [PMID: 38694536 PMCID: PMC11061447 DOI: 10.3389/fncel.2024.1363219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2023] [Accepted: 03/27/2024] [Indexed: 05/04/2024] Open
Abstract
Introduction Cochlear afferent synapses connecting inner hair cells to spiral ganglion neurons are susceptible to excitotoxic trauma on exposure to loud sound, resulting in a noise-induced cochlear synaptopathy (NICS). Here we assessed the ability of cyclic AMP-dependent protein kinase (PKA) signaling to promote cochlear synapse regeneration, inferred from its ability to promote axon regeneration in axotomized CNS neurons, another system refractory to regeneration. Methods We mimicked NICS in vitro by applying a glutamate receptor agonist, kainic acid (KA) to organotypic cochlear explant cultures and experimentally manipulated cAMP signaling to determine whether PKA could promote synapse regeneration. We then delivered the cAMP phosphodiesterase inhibitor rolipram via implanted subcutaneous minipumps in noise-exposed CBA/CaJ mice to test the hypothesis that cAMP signaling could promote cochlear synapse regeneration in vivo. Results We showed that the application of the cell membrane-permeable cAMP agonist 8-cpt-cAMP or the cAMP phosphodiesterase inhibitor rolipram promotes significant regeneration of synapses in vitro within twelve hours after their destruction by KA. This is independent of neurotrophin-3, which also promotes synapse regeneration. Moreover, of the two independent signaling effectors activated by cAMP - the cAMP Exchange Protein Activated by cAMP and the cAMP-dependent protein kinase - it is the latter that mediates synapse regeneration. Finally, we showed that systemic delivery of rolipram promotes synapse regeneration in vivo following NICS. Discussion In vitro experiments show that cAMP signaling promotes synapse regeneration after excitotoxic destruction of cochlear synapses and does so via PKA signaling. The cAMP phosphodiesterase inhibitor rolipram promotes synapse regeneration in vivo in noise-exposed mice. Systemic administration of rolipram or similar compounds appears to provide a minimally invasive therapeutic approach to reversing synaptopathy post-noise.
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Affiliation(s)
| | | | | | - Steven H. Green
- Department of Biology, University of Iowa, Iowa City, IA, United States
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Rommelspacher H, Bera S, Brommer B, Ward R, Kwiatkowska M, Zygmunt T, Theden F, Üsekes B, Eren N, Nieratschker M, Arnoldner C, Plontke SK, Hellmann-Regen J, Schlingensiepen R. A single dose of AC102 restores hearing in a guinea pig model of noise-induced hearing loss to almost prenoise levels. Proc Natl Acad Sci U S A 2024; 121:e2314763121. [PMID: 38557194 PMCID: PMC11009624 DOI: 10.1073/pnas.2314763121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Accepted: 01/29/2024] [Indexed: 04/04/2024] Open
Abstract
Although sudden sensorineural hearing loss (SSNHL) is a serious condition, there are currently no approved drugs for its treatment. Nevertheless, there is a growing understanding that the cochlear pathologies that underlie SSNHL include apoptotic death of sensory outer hair cells (OHCs) as well as loss of ribbon synapses connecting sensory inner hair cells (IHCs) and neurites of the auditory nerve, designated synaptopathy. Noise-induced hearing loss (NIHL) is a common subtype of SSNHL and is widely used to model hearing loss preclinically. Here, we demonstrate that a single interventive application of a small pyridoindole molecule (AC102) into the middle ear restored auditory function almost to prenoise levels in a guinea pig model of NIHL. AC102 prevented noise-triggered loss of OHCs and reduced IHC synaptopathy suggesting a role of AC102 in reconnecting auditory neurons to their sensory target cells. Notably, AC102 exerted its therapeutic properties over a wide frequency range. Such strong improvements in hearing have not previously been demonstrated for other therapeutic agents. In vitro experiments of a neuronal damage model revealed that AC102 protected cells from apoptosis and promoted neurite growth. These effects may be explained by increased production of adenosine triphosphate, indicating improved mitochondrial function, and reduced levels of reactive-oxygen species which prevents the apoptotic processes responsible for OHC death. This action profile of AC102 might be causal for the observed hearing recovery in in vivo models.
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Affiliation(s)
| | - Sujoy Bera
- AudioCure Pharma GmbH, Berlin10115, Germany
| | | | | | | | | | | | - Berk Üsekes
- AudioCure Pharma GmbH, Berlin10115, Germany
- Department of Psychiatry and Psychotherapy, Section Clinical Neurobiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Campus Benjamin Franklin, Berlin12203, Germany
| | - Neriman Eren
- AudioCure Pharma GmbH, Berlin10115, Germany
- Department of Psychiatry and Psychotherapy, Section Clinical Neurobiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Campus Benjamin Franklin, Berlin12203, Germany
| | - Michael Nieratschker
- Department of Otorhinolaryngology, Head and Neck Surgery, Vienna General Hospital, Medical University of Vienna, Vienna1090, Austria
| | - Christoph Arnoldner
- Department of Otorhinolaryngology, Head and Neck Surgery, Vienna General Hospital, Medical University of Vienna, Vienna1090, Austria
| | - Stefan K. Plontke
- Department of Otorhinolaryngology, Head and Neck Surgery, Martin Luther University Halle-Wittenberg, Halle06120, Germany
| | - Julian Hellmann-Regen
- Department of Psychiatry and Psychotherapy, Section Clinical Neurobiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Campus Benjamin Franklin, Berlin12203, Germany
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Wu PZ, Liberman LD, Liberman MC. Noise-induced synaptic loss and its post-exposure recovery in CBA/CaJ vs. C57BL/6J mice. Hear Res 2024; 445:108996. [PMID: 38547565 PMCID: PMC11024800 DOI: 10.1016/j.heares.2024.108996] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Revised: 03/11/2024] [Accepted: 03/22/2024] [Indexed: 04/07/2024]
Abstract
Acute noise-induced loss of synapses between inner hair cells (IHCs) and auditory nerve fibers (ANFs) has been documented in several strains of mice, but the extent of post-exposure recovery reportedly varies dramatically. If such inter-strain heterogeneity is real, it could be exploited to probe molecular pathways mediating neural remodeling in the adult cochlea. Here, we compared synaptopathy repair in CBA/CaJ vs. C57BL/6J, which are at opposite ends of the reported recovery spectrum. We evaluated C57BL/6J mice 0 h, 24 h, 2 wks or 8 wks after exposure for 2 h to octave-band noise (8-16 kHz) at either 90, 94 or 98 dB SPL, to compare with analogous post-exposure results in CBA/CaJ at 98 or 101 dB. We counted pre- and post-synaptic puncta in immunostained cochleas, using machine learning to classify paired (GluA2 and CtBP2) vs. orphan (CtBP2 only) puncta, and batch-processing to quantify immunostaining intensity. At 98 dB, both strains show ongoing loss of ribbons and synapses between 0 and 24 h, followed by partial recovery, however the extent and degree of these changes were greater in C57BL/6J. Much of the synaptic recovery is due to transient reduction in GluA2 intensity in synaptopathic regions. In contrast, CtBP2 intensity showed only transient increases (at 2 wks). Neurofilament staining revealed transient extension of ANF terminals in C57BL/6J, but not in CBA/CaJ, peaking at 24 h and reverting by 2 wks. Thus, although interstrain differences in synapse recovery are dominated by reversible changes in GluA2 receptor levels, the neurite extension seen in C57BL/6J suggests a qualitative difference in regenerative capacity.
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Affiliation(s)
- Pei-Zhe Wu
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA 02114, USA; Department of Otolaryngology, Harvard Medical School, Boston, MA 02115, USA
| | - Leslie D Liberman
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA 02114, USA
| | - M Charles Liberman
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA 02114, USA; Department of Otolaryngology, Harvard Medical School, Boston, MA 02115, USA.
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Saidia AR, François F, Casas F, Mechaly I, Venteo S, Veechi JT, Ruel J, Puel JL, Wang J. Oxidative Stress Plays an Important Role in Glutamatergic Excitotoxicity-Induced Cochlear Synaptopathy: Implication for Therapeutic Molecules Screening. Antioxidants (Basel) 2024; 13:149. [PMID: 38397748 PMCID: PMC10886292 DOI: 10.3390/antiox13020149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 01/12/2024] [Accepted: 01/20/2024] [Indexed: 02/25/2024] Open
Abstract
The disruption of the synaptic connection between the sensory inner hair cells (IHCs) and the auditory nerve fiber terminals of the type I spiral ganglion neurons (SGN) has been observed early in several auditory pathologies (e.g., noise-induced or ototoxic drug-induced or age-related hearing loss). It has been suggested that glutamate excitotoxicity may be an inciting element in the degenerative cascade observed in these pathological cochlear conditions. Moreover, oxidative damage induced by free hydroxyl radicals and nitric oxide may dramatically enhance cochlear damage induced by glutamate excitotoxicity. To investigate the underlying molecular mechanisms involved in cochlear excitotoxicity, we examined the molecular basis responsible for kainic acid (KA, a full agonist of AMPA/KA-preferring glutamate receptors)-induced IHC synapse loss and degeneration of the terminals of the type I spiral ganglion afferent neurons using a cochlear explant culture from P3 mouse pups. Our results demonstrated that disruption of the synaptic connection between IHCs and SGNs induced increased levels of oxidative stress, as well as altered both mitochondrial function and neurotrophin signaling pathways. Additionally, the application of exogenous antioxidants and neurotrophins (NT3, BDNF, and small molecule TrkB agonists) clearly increases synaptogenesis. These results suggest that understanding the molecular pathways involved in cochlear excitotoxicity is of crucial importance for the future clinical trials of drug interventions for auditory synaptopathies.
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Affiliation(s)
- Anissa Rym Saidia
- Institute for Neurosciences of Montpellier (INM), INSERM U1298, University Montpellier, 34295 Montpellier, France; (F.F.); (I.M.); (S.V.); (J.T.V.); (J.-L.P.)
| | - Florence François
- Institute for Neurosciences of Montpellier (INM), INSERM U1298, University Montpellier, 34295 Montpellier, France; (F.F.); (I.M.); (S.V.); (J.T.V.); (J.-L.P.)
| | - François Casas
- INRA, UMR 866 Dynamique Musculaire et Métabolisme, 34060 Montpellier, France;
| | - Ilana Mechaly
- Institute for Neurosciences of Montpellier (INM), INSERM U1298, University Montpellier, 34295 Montpellier, France; (F.F.); (I.M.); (S.V.); (J.T.V.); (J.-L.P.)
| | - Stéphanie Venteo
- Institute for Neurosciences of Montpellier (INM), INSERM U1298, University Montpellier, 34295 Montpellier, France; (F.F.); (I.M.); (S.V.); (J.T.V.); (J.-L.P.)
| | - Joseph T. Veechi
- Institute for Neurosciences of Montpellier (INM), INSERM U1298, University Montpellier, 34295 Montpellier, France; (F.F.); (I.M.); (S.V.); (J.T.V.); (J.-L.P.)
| | - Jérôme Ruel
- Centre de Recherche en CardioVasculaire et Nutrition, Aix-Marseille Université-INSERM, 1263-INRAE 1260, 13385 Marseille, France;
| | - Jean-Luc Puel
- Institute for Neurosciences of Montpellier (INM), INSERM U1298, University Montpellier, 34295 Montpellier, France; (F.F.); (I.M.); (S.V.); (J.T.V.); (J.-L.P.)
| | - Jing Wang
- Institute for Neurosciences of Montpellier (INM), INSERM U1298, University Montpellier, 34295 Montpellier, France; (F.F.); (I.M.); (S.V.); (J.T.V.); (J.-L.P.)
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10
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Yang ZJ, Zhao CL, Liang WQ, Chen ZR, Du ZD, Gong SS. ROS-induced oxidative stress and mitochondrial dysfunction: a possible mechanism responsible for noise-induced ribbon synaptic damage. Am J Transl Res 2024; 16:272-284. [PMID: 38322575 PMCID: PMC10839402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Accepted: 01/05/2024] [Indexed: 02/08/2024]
Abstract
Evidence suggests that damage to the ribbon synapses (RS) may be the main cause of auditory dysfunction in noise-induced hearing loss (NIHL). Oxidative stress is implicated in the pathophysiology of synaptic damage. However, the relationship between oxidative stress and RS damage in NIHL remains unclear. To investigate the hypothesis that noise-induced oxidative stress is a key factor in synaptic damage within the inner ear, we conducted a study using mice subjected to single or repeated noise exposure (NE). We assessed auditory function using auditory brainstem response (ABR) test and examined cochlear morphology by immunofluorescence staining. The results showed that mice that experienced a single NE exhibited a threshold shift and recovered within two weeks. The ABR wave I latencies were prolonged, and the amplitudes decreased, suggesting RS dysfunction. These changes were also demonstrated by the loss of RS as evidenced by immunofluorescence staining. However, we observed threshold shifts that did not return to baseline levels following secondary NE. Additionally, ABR wave I latencies and amplitudes exhibited notable changes. Immunofluorescence staining indicated not only severe damage to RS but also loss of outer hair cells. We also noted decreased T-AOC, ATP, and mitochondrial membrane potential levels, alongside increased hydrogen peroxide concentrations post-NE. Furthermore, the expression levels of 4-HNE and 8-OHdG in the cochlea were notably elevated. Collectively, our findings suggest that the production of reactive oxygen species leads to oxidative damage in the cochlea. This mitochondrial dysfunction consequently contributes to the loss of RS, precipitating an early onset of NIHL.
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Affiliation(s)
- Zi-Jing Yang
- Department of Otolaryngology Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical UniversityBeijing 100050, China
- Clinical Center for Hearing Loss, Capital Medical UniversityBeijing 100050, China
| | - Chun-Li Zhao
- Department of Otolaryngology Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical UniversityBeijing 100050, China
- Clinical Center for Hearing Loss, Capital Medical UniversityBeijing 100050, China
| | - Wen-Qi Liang
- Department of Otolaryngology Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical UniversityBeijing 100050, China
- Clinical Center for Hearing Loss, Capital Medical UniversityBeijing 100050, China
| | - Zhong-Rui Chen
- Department of Otolaryngology Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical UniversityBeijing 100050, China
- Clinical Center for Hearing Loss, Capital Medical UniversityBeijing 100050, China
| | - Zheng-De Du
- Department of Otolaryngology Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical UniversityBeijing 100050, China
- Clinical Center for Hearing Loss, Capital Medical UniversityBeijing 100050, China
| | - Shu-Sheng Gong
- Department of Otolaryngology Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical UniversityBeijing 100050, China
- Clinical Center for Hearing Loss, Capital Medical UniversityBeijing 100050, China
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11
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Walia A, Shew MA, Varghese J, Ioerger P, Lefler SM, Ortmann AJ, Herzog JA, Buchman CA. Improved Cochlear Implant Performance Estimation Using Tonotopic-Based Electrocochleography. JAMA Otolaryngol Head Neck Surg 2023; 149:1120-1129. [PMID: 37856099 PMCID: PMC10587831 DOI: 10.1001/jamaoto.2023.2988] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Accepted: 08/04/2023] [Indexed: 10/20/2023]
Abstract
Importance Cochlear implantation produces remarkable results in postlingual deafness, although auditory outcomes vary. Electrocochleography (ECochG) has emerged as a valuable tool for assessing the cochlear-neural substrate and evaluating patient prognosis. Objective To assess whether ECochG-total response (ECochG-TR) recorded at the best-frequency electrode (BF-ECochG-TR) correlates more strongly with speech perception performance than ECochG-TR measured at the round window (RW-ECochG-TR). Design, Setting, and Participants This single-center cross-sectional study recruited 142 patients from July 1, 2021, to April 30, 2022, with 1-year follow-up. Exclusions included perilymph suctioning, crimped sound delivery tubes, non-native English speakers, inner ear malformations, nonpatent external auditory canals, or cochlear implantation revision surgery. Exposures Cochlear implantation. Main Outcomes and Measures Speech perception testing, including the consonant-nucleus-consonant (CNC) words test, AzBio sentences in quiet, and AzBio sentences in noise plus 10-dB signal to noise ratio (with low scores indicating poor performance and high scores indicating excellent performance on all tests), at 6 months postoperatively; and RW-ECochG-TR and BF-ECochG-TR (measured for 250, 500, 1000, and 2000 Hz). Results A total of 109 of the 142 eligible postlingual adults (mean [SD] age, 68.7 [15.8] years; 67 [61.5%] male) were included in the study. Both BF-ECochG-TR and RW-ECochG-TR were correlated with 6-month CNC scores (BF-ECochG-TR: r = 0.74; 95% CI, 0.62-0.82; RW-ECochG-TR: r = 0.67; 95% CI, 0.54-0.76). A multivariate model incorporating age, duration of hearing loss, and angular insertion depth did not outperform BF-ECochG-TR or RW-ECochG-TR alone. The BF-ECochG-TR correlation with CNC scores was significantly stronger than the RW-ECochG-TR correlation (r difference = -0.18; 95% CI, -0.31 to -0.01; z = -2.02). More moderate correlations existed between 6-month AzBio scores in noise, Montreal Cognitive Assessment (MoCA) scores (r = 0.46; 95% CI, 0.29-0.60), and BF-ECochG-TR (r = 0.42; 95% CI, 0.22-0.58). MoCA and the interaction between BF-ECochG-TR and MoCA accounted for a substantial proportion of variability in AzBio scores in noise at 6 months (R2 = 0.50; 95% CI, 0.36-0.61). Conclusions and Relevance In this case series, BF-ECochG-TR was identified as having a stronger correlation with cochlear implantation performance than RW-ECochG-TR, although both measures highlight the critical role of the cochlear-neural substrate on outcomes. Demographic, audiologic, and surgical factors demonstrated weak correlations with cochlear implantation performance, and performance in noise was found to require a robust cochlear-neural substrate (BF-ECochG-TR) as well as sufficient cognitive capacity (MoCA). Future cochlear implantation studies should consider these variables when assessing performance and related interventions.
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Affiliation(s)
- Amit Walia
- Department of Otolaryngology–Head and Neck Surgery, Washington University School of Medicine in St Louis, St Louis, Missouri
| | - Matthew A. Shew
- Department of Otolaryngology–Head and Neck Surgery, Washington University School of Medicine in St Louis, St Louis, Missouri
| | - Jordan Varghese
- Department of Otolaryngology–Head and Neck Surgery, Washington University School of Medicine in St Louis, St Louis, Missouri
| | - Patrick Ioerger
- Department of Otolaryngology–Head and Neck Surgery, Washington University School of Medicine in St Louis, St Louis, Missouri
| | - Shannon M. Lefler
- Department of Otolaryngology–Head and Neck Surgery, Washington University School of Medicine in St Louis, St Louis, Missouri
| | - Amanda J. Ortmann
- Department of Otolaryngology–Head and Neck Surgery, Washington University School of Medicine in St Louis, St Louis, Missouri
| | - Jacques A. Herzog
- Department of Otolaryngology–Head and Neck Surgery, Washington University School of Medicine in St Louis, St Louis, Missouri
| | - Craig A. Buchman
- Department of Otolaryngology–Head and Neck Surgery, Washington University School of Medicine in St Louis, St Louis, Missouri
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12
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Moverman DJ, Liberman LD, Kraemer S, Corfas G, Liberman MC. Ultrastructure of noise-induced cochlear synaptopathy. Sci Rep 2023; 13:19456. [PMID: 37945811 PMCID: PMC10636047 DOI: 10.1038/s41598-023-46859-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Accepted: 11/06/2023] [Indexed: 11/12/2023] Open
Abstract
Acoustic overexposure can eliminate synapses between inner hair cells (IHCs) and auditory nerve fibers (ANFs), even if hair-cell function recovers. This synaptopathy has been extensively studied by confocal microscopy, however, understanding the nature and sequence of damage requires ultrastructural analysis. Here, we used focused ion-beam scanning electron microscopy to mill, image, segment and reconstruct ANF terminals in mice, 1 day and 1 week after synaptopathic exposure (8-16 kHz, 98 dB SPL). At both survivals, ANF terminals were normal in number, but 62% and 53%, respectively, lacked normal synaptic specializations. Most non-synapsing fibers (57% and 48% at 1 day and 1 week) remained in contact with an IHC and contained healthy-looking organelles. ANFs showed a transient increase in mitochondrial content (51%) and efferent innervation (34%) at 1 day. Fibers maintaining synaptic connections showed hypertrophy of pre-synaptic ribbons at both 1 day and 1 week. Non-synaptic fibers were lower in mitochondrial content and typically on the modiolar side of the IHC, where ANFs with high-thresholds and low spontaneous rates are normally found. Even 1 week post-exposure, many ANF terminals remained in IHC contact despite loss of synaptic specializations, thus, regeneration efforts at early post-exposure times should concentrate on synaptogenesis rather than neurite extension.
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Affiliation(s)
- Daniel J Moverman
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, 243 Charles St., Boston, MA, 02114-3096, USA
| | - Leslie D Liberman
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, 243 Charles St., Boston, MA, 02114-3096, USA
| | - Stephan Kraemer
- Center for Nanoscale Systems, Harvard College, Cambridge, MA, 02138, USA
| | - Gabriel Corfas
- Department of Otolaryngology-Head and Neck Surgery, Kresge Hearing Research Institute, University of Michigan, Ann Arbor, MI, USA
| | - M Charles Liberman
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, 243 Charles St., Boston, MA, 02114-3096, USA.
- Department of Otolaryngology-Head and Neck Surgery, Harvard Medical School, Boston, MA, 02115, USA.
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13
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Wu PZ, O'Malley JT, Liberman MC. Neural Degeneration in Normal-Aging Human Cochleas: Machine-Learning Counts and 3D Mapping in Archival Sections. J Assoc Res Otolaryngol 2023; 24:499-511. [PMID: 37957485 PMCID: PMC10695900 DOI: 10.1007/s10162-023-00909-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Accepted: 09/03/2023] [Indexed: 11/15/2023] Open
Abstract
Quantifying the survival patterns of spiral ganglion cells (SGCs), the cell bodies of auditory-nerve fibers, is critical to studies of sensorineural hearing loss, especially in human temporal bones. The classic method of manual counting is tedious, and, although stereology approaches can be faster, they can only be used to estimate total cell numbers per cochlea. Here, a machine-learning algorithm that automatically identifies, counts, and maps the SGCs in digitized images of semi-serial human temporal-bone sections not only speeds the analysis, with no loss of accuracy, but also allows 3D visualization of the SGCs and fine-grained mapping to cochlear frequency. Applying the algorithm to 62 normal-aging human ears shows significantly faster degeneration of SGCs in the basal than the apical half of the cochlea. Comparison to fiber counts in the same ears shows that the fraction of surviving SGCs lacking a peripheral axon steadily increases with age, reaching more than 50% in the apical cochlea and almost 66% in basal regions.
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Affiliation(s)
- Pei-Zhe Wu
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear Infirmary, 243 Charles St., Boston, MA, 02114-3096, USA.
- Department of Otolaryngology, Harvard Medical School, Boston, MA, 02115, USA.
| | - Jennifer T O'Malley
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear Infirmary, 243 Charles St., Boston, MA, 02114-3096, USA
- Department of Otolaryngology, Harvard Medical School, Boston, MA, 02115, USA
| | - M Charles Liberman
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear Infirmary, 243 Charles St., Boston, MA, 02114-3096, USA
- Department of Otolaryngology, Harvard Medical School, Boston, MA, 02115, USA
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14
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Gunewardene N, Ma Y, Lam P, Wagstaff S, Cortez-Jugo C, Hu Y, Caruso F, Richardson RT, Wise AK. Developing the supraparticle technology for round window-mediated drug administration into the cochlea. J Control Release 2023; 361:621-635. [PMID: 37572963 DOI: 10.1016/j.jconrel.2023.08.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Revised: 08/04/2023] [Accepted: 08/09/2023] [Indexed: 08/14/2023]
Abstract
The semi-permeable round window membrane (RWM) is the gateway to the cochlea. Although the RWM is considered a minimally invasive and clinically accepted route for localised drug delivery to the cochlea, overcoming this barrier is challenging, hindering development of effective therapies for hearing loss. Neurotrophin 3 (NT3) is an emerging treatment option for hearing loss, but its therapeutic effect relies on sustained delivery across the RWM into the cochlea. Silica supraparticles (SPs) are drug delivery carriers capable of providing long-term NT3 delivery, when injected directly into the guinea pig cochlea. However, for clinical translation, a RWM delivery approach is desirable. Here, we aimed to test approaches to improve the longevity and biodistribution of NT3 inside the cochlea after RWM implantation of SPs in guinea pigs and cats. Three approaches were tested (i) coating the SPs to slow drug release (ii) improving the retention of SPs on the RWM using a clinically approved gel formulation and (iii) permeabilising the RWM with hyaluronic acid. A radioactive tracer (iodine 125: 125I) tagged to NT3 (125I NT3) was loaded into the SPs to characterise drug pharmacokinetics in vitro and in vivo. The neurotrophin-loaded SPs were coated using a chitosan and alginate layer-by-layer coating strategy, named as '(Chi/Alg)SPs', to promote long term drug release. The guinea pigs were implanted with 5× 125I NT3 loaded (Chi/Alg) SPs on the RWM, while cats were implanted with 30× (Chi/Alg) SPs. A cohort of animals were also implanted with SPs (controls). We found that the NT3 loaded (Chi/Alg)SPs exhibited a more linear release profile compared to NT3 loaded SPs alone. The 125I NT3 loaded (Chi/Alg)SPs in fibrin sealant had efficient drug loading (~5 μg of NT3 loaded per SP that weights ~50 μg) and elution capacities (~49% over one month) in vitro. Compared to the SPs in fibrin sealant, the (Chi/Alg)SPs in fibrin sealant had a significantly slower 125I NT3 drug release profile over the first 7 days in vitro (~12% for (Chi/Alg) SPs in fibrin sealant vs ~43% for SPs in fibrin sealant). One-month post-implantation of (Chi/Alg) SPs, gamma count measurements revealed an average of 0.3 μg NT3 remained in the guinea pig cochlea, while for the cat, 1.3 μg remained. Histological analysis of cochlear tissue revealed presence of a 125I NT3 signal localised in the basilar membrane of the lower basal turn in some cochleae after 4 weeks in guinea pigs and 8 weeks in cats. Comparatively, and in contrast to the in vitro release data, implantation of the SPs presented better NT3 retention and distribution inside the cochlea in both the guinea pigs and cats. No significant difference in drug entry was observed upon acute treatment of the RWM with hyaluronic acid. Collectively, our findings indicate that SPs and (Chi/Alg)SPs can facilitate drug transfer across the RWM, with detectable levels inside the cat cochlea even after 8 weeks with the intracochlear approach. This is the first study to examine neurotrophin pharmacokinetics in the cochlea for such an extended period of times in these two animal species. Whilst promising, we note that outcomes between animals were variable, and opposing results were found between in vitro and in vivo release studies. These findings have important clinical ramifications, emphasising the need to understand the physical properties and mechanics of this complex barrier in parallel with the development of therapies for hearing loss.
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Affiliation(s)
- Niliksha Gunewardene
- Bionics Institute, East Melbourne, Victoria 3002, Australia; Department of Medical Bionics, The University of Melbourne, Fitzroy, Victoria 3065, Australia.
| | - Yutian Ma
- Bionics Institute, East Melbourne, Victoria 3002, Australia; Department of Chemical Engineering, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Patrick Lam
- Bionics Institute, East Melbourne, Victoria 3002, Australia
| | | | - Christina Cortez-Jugo
- Department of Chemical Engineering, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Yingjie Hu
- Bionics Institute, East Melbourne, Victoria 3002, Australia; Department of Medical Bionics, The University of Melbourne, Fitzroy, Victoria 3065, Australia; Department of Chemical Engineering, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Frank Caruso
- Department of Chemical Engineering, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Rachael T Richardson
- Bionics Institute, East Melbourne, Victoria 3002, Australia; Department of Medical Bionics, The University of Melbourne, Fitzroy, Victoria 3065, Australia; Department of Surgery (Otolaryngology), University of Melbourne, The Royal Victorian Eye and Ear Hospital, East Melbourne, Victoria 3002, Australia
| | - Andrew K Wise
- Bionics Institute, East Melbourne, Victoria 3002, Australia; Department of Medical Bionics, The University of Melbourne, Fitzroy, Victoria 3065, Australia.
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15
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Haggerty RA, Hutson KA, Riggs WJ, Brown KD, Pillsbury HC, Adunka OF, Buchman CA, Fitzpatrick DC. Assessment of cochlear synaptopathy by electrocochleography to low frequencies in a preclinical model and human subjects. Front Neurol 2023; 14:1104574. [PMID: 37483448 PMCID: PMC10361575 DOI: 10.3389/fneur.2023.1104574] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Accepted: 06/19/2023] [Indexed: 07/25/2023] Open
Abstract
Cochlear synaptopathy is the loss of synapses between the inner hair cells and the auditory nerve despite survival of sensory hair cells. The findings of extensive cochlear synaptopathy in animals after moderate noise exposures challenged the long-held view that hair cells are the cochlear elements most sensitive to insults that lead to hearing loss. However, cochlear synaptopathy has been difficult to identify in humans. We applied novel algorithms to determine hair cell and neural contributions to electrocochleographic (ECochG) recordings from the round window of animal and human subjects. Gerbils with normal hearing provided training and test sets for a deep learning algorithm to detect the presence of neural responses to low frequency sounds, and an analytic model was used to quantify the proportion of neural and hair cell contributions to the ECochG response. The capacity to detect cochlear synaptopathy was validated in normal hearing and noise-exposed animals by using neurotoxins to reduce or eliminate the neural contributions. When the analytical methods were applied to human surgical subjects with access to the round window, the neural contribution resembled the partial cochlear synaptopathy present after neurotoxin application in animals. This result demonstrates the presence of viable hair cells not connected to auditory nerve fibers in human subjects with substantial hearing loss and indicates that efforts to regenerate nerve fibers may find a ready cochlear substrate for innervation and resumption of function.
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Affiliation(s)
- Raymond A. Haggerty
- Department of Otolaryngology, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Kendall A. Hutson
- Department of Otolaryngology, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - William J. Riggs
- Department of Otolaryngology, The Ohio State University, Columbus, OH, United States
| | - Kevin D. Brown
- Department of Otolaryngology, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
- University of North Carolina School of Medicine, Chapel Hill, NC, United States
| | - Harold C. Pillsbury
- Department of Otolaryngology, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
- University of North Carolina School of Medicine, Chapel Hill, NC, United States
| | - Oliver F. Adunka
- Department of Otolaryngology, The Ohio State University, Columbus, OH, United States
| | - Craig A. Buchman
- Department of Otolaryngology, Washington University in St. Louis, St. Louis, MO, United States
| | - Douglas C. Fitzpatrick
- Department of Otolaryngology, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
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16
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Kempfle JS, Jung DH. Experimental drugs for the prevention or treatment of sensorineural hearing loss. Expert Opin Investig Drugs 2023; 32:643-654. [PMID: 37598357 DOI: 10.1080/13543784.2023.2242253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Accepted: 07/26/2023] [Indexed: 08/22/2023]
Abstract
INTRODUCTION Sensorineural hearing loss results in irreversible loss of inner ear hair cells and spiral ganglion neurons. Reduced sound detection and speech discrimination can span all ages, and sensorineural hearing rehabilitation is limited to amplification with hearing aids or cochlear implants. Recent insights into experimental drug treatments for inner ear regeneration and otoprotection have paved the way for clinical trials in order to restore a more physiological hearing experience. Paired with the development of innovative minimally invasive approaches for drug delivery to the inner ear, new, emerging treatments for hearing protection and restoration are within reach. AREAS COVERED This expert opinion provides an overview of the latest experimental drug therapies to protect from and to restore sensorineural hearing loss. EXPERT OPINION The degree and type of cellular damage to the cochlea, the responsiveness of remaining, endogenous cells to regenerative treatments, and the duration of drug availability within cochlear fluids will determine the success of hearing protection or restoration.
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Affiliation(s)
- Judith S Kempfle
- Department of Otolaryngology, Massachusetts Eye and Ear, Boston, MA, USA
- Department of Otolaryngology, Head & Neck Surgery, Harvard Medical School, Boston, MA, USA
- Department of Otolaryngology, UMass Memorial Medical Center, Worcester, MA, USA
- Department of Otolaryngology, Head & Neck Surgery, University of Massachusetts Medical School, Worcester, MA, USA
| | - David H Jung
- Department of Otolaryngology, Massachusetts Eye and Ear, Boston, MA, USA
- Department of Otolaryngology, Head & Neck Surgery, Harvard Medical School, Boston, MA, USA
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17
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Xu K, Xu B, Gu J, Wang X, Yu D, Chen Y. Intrinsic mechanism and pharmacologic treatments of noise-induced hearing loss. Theranostics 2023; 13:3524-3549. [PMID: 37441605 PMCID: PMC10334830 DOI: 10.7150/thno.83383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Accepted: 06/12/2023] [Indexed: 07/15/2023] Open
Abstract
Noise accounts for one-third of hearing loss worldwide. Regretfully, noise-induced hearing loss (NIHL) is deemed to be irreversible due to the elusive pathogenic mechanisms that have not been fully elucidated. The complex interaction between genetic and environmental factors, which influences numerous downstream molecular and cellular events, contributes to the NIHL. In clinical settings, there are no effective therapeutic drugs other than steroids, which are the only treatment option for patients with NIHL. Therefore, the need for treatment of NIHL that is currently unmet, along with recent progress in our understanding of the underlying regulatory mechanisms, has led to a lot of new literatures focusing on this therapeutic field. The emergence of novel technologies that modify local drug delivery to the inner ear has led to the development of promising therapeutic approaches, which are currently under clinical investigation. In this comprehensive review, we focus on outlining and analyzing the basics and potential therapeutics of NIHL, as well as the application of biomaterials and nanomedicines in inner ear drug delivery. The objective of this review is to provide an incentive for NIHL's fundamental research and future clinical translation.
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Affiliation(s)
- Ke Xu
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
- Ear Institute, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Baoying Xu
- Materdicine Lab, School of Life Sciences, Shanghai University, Shanghai, China
| | - Jiayi Gu
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
- Ear Institute, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Xueling Wang
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
- Ear Institute, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Dehong Yu
- Materdicine Lab, School of Life Sciences, Shanghai University, Shanghai, China
| | - Yu Chen
- Materdicine Lab, School of Life Sciences, Shanghai University, Shanghai, China
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Choi JE, Carpena NT, Lee JH, Chang SY, Lee MY, Jung JY, Chung WH. Round-window delivery of lithium chloride regenerates cochlear synapses damaged by noise-induced excitotoxic trauma via inhibition of the NMDA receptor in the rat. PLoS One 2023; 18:e0284626. [PMID: 37216352 DOI: 10.1371/journal.pone.0284626] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Accepted: 04/04/2023] [Indexed: 05/24/2023] Open
Abstract
Noise exposure can destroy the synaptic connections between hair cells and auditory nerve fibers without damaging the hair cells, and this synaptic loss could contribute to difficult hearing in noisy environments. In this study, we investigated whether delivering lithium chloride to the round-window can regenerate synaptic loss of cochlea after acoustic overexposure. Our rat animal model of noise-induced cochlear synaptopathy caused about 50% loss of synapses in the cochlear basal region without damaging hair cells. We locally delivered a single treatment of poloxamer 407 (vehicle) containing lithium chloride (either 1 mM or 2 mM) to the round-window niche 24 hours after noise exposure. Controls included animals exposed to noise who received only the vehicle. Auditory brainstem responses were measured 3 days, 1 week, and 2 weeks post-exposure treatment, and cochleas were harvested 1 week and 2 weeks post-exposure treatment for histological analysis. As documented by confocal microscopy of immunostained ribbon synapses, local delivery of 2 mM lithium chloride produced synaptic regeneration coupled with corresponding functional recovery, as seen in the suprathreshold amplitude of auditory brainstem response wave 1. Western blot analyses revealed that 2 mM lithium chloride suppressed N-methyl-D-aspartate (NMDA) receptor expression 7 days after noise-exposure. Thus, round-window delivery of lithium chloride using poloxamer 407 reduces cochlear synaptic loss after acoustic overexposure by inhibiting NMDA receptor activity in rat model.
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Affiliation(s)
- Ji Eun Choi
- Department of Otolaryngology Head and Neck Surgery, Dankook University Hospital, College of Medicine, Dankook University, Cheonan, South Korea
- Multi-modality Treatment Research Center for Auditory/Vestibular Disease, College of Medicine, Dankook University, Cheonan, South Korea
| | - Nathaniel T Carpena
- Multi-modality Treatment Research Center for Auditory/Vestibular Disease, College of Medicine, Dankook University, Cheonan, South Korea
| | - Jae-Hun Lee
- Center for Cognition and Sociality, Institute for Basic Science, Daejeon, Republic of Korea
| | - So-Young Chang
- Multi-modality Treatment Research Center for Auditory/Vestibular Disease, College of Medicine, Dankook University, Cheonan, South Korea
| | - Min Young Lee
- Department of Otolaryngology Head and Neck Surgery, Dankook University Hospital, College of Medicine, Dankook University, Cheonan, South Korea
- Multi-modality Treatment Research Center for Auditory/Vestibular Disease, College of Medicine, Dankook University, Cheonan, South Korea
| | - Jae Yun Jung
- Department of Otolaryngology Head and Neck Surgery, Dankook University Hospital, College of Medicine, Dankook University, Cheonan, South Korea
- Multi-modality Treatment Research Center for Auditory/Vestibular Disease, College of Medicine, Dankook University, Cheonan, South Korea
| | - Won-Ho Chung
- Department of Otorhinolaryngology-Head and Neck Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
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Uribe PM, Hudson AM, Lockard G, Jiang M, Harding J, Steyger PS, Coffin AB. Hepatocyte growth factor mimetic confers protection from aminoglycoside-induced hair cell death in vitro. Hear Res 2023; 434:108786. [PMID: 37192594 DOI: 10.1016/j.heares.2023.108786] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 04/18/2023] [Accepted: 05/05/2023] [Indexed: 05/18/2023]
Abstract
Loss of sensory hair cells from exposure to certain licit drugs, such as aminoglycoside antibiotics, can result in permanent hearing damage. Exogenous application of the neurotrophic molecule hepatocyte growth factor (HGF) promotes neuronal cell survival in a variety of contexts, including protecting hair cells from aminoglycoside ototoxicity. HGF itself is not an ideal therapeutic due to a short half-life and limited blood-brain barrier permeability. MM-201 is a chemically stable, blood-brain barrier permeable, synthetic HGF mimetic that serves as a functional ligand to activate the HGF receptor and its downstream signaling cascade. We previously demonstrated that MM-201 robustly protects zebrafish lateral line hair cells from aminoglycoside ototoxicity. Here, we examined the ability of MM-201 to protect mammalian sensory hair cells from aminoglycoside damage to further evaluate MM-201's clinical potential. We found that MM-201 exhibited dose-dependent protection from neomycin and gentamicin ototoxicity in mature mouse utricular explants. MM-201's protection was reduced following inhibition of mTOR, a downstream target of HGF receptor activation, implicating the activation of endogenous intracellular substrates by MM-201 as critical for the observed protection. We then asked if MM-201 altered the bactericidal properties of aminoglycosides. Using either plate or liquid growth assays we found that MM-201 did not alter the bactericidal efficacy of aminoglycoside antibiotics at therapeutically relevant concentrations. We therefore assessed the protective capacity of MM-201 in an in vivo mouse model of kanamycin ototoxicity. In contrast to our in vitro data, MM-201 did not attenuate kanamycin ototoxicity in vivo. Further, we found that MM-201 was ototoxic to mice across the dose range tested here. These data suggest species- and tissue-specific differences in otoprotective capacity. Next generation HGF mimetics are in clinical trials for neurodegenerative diseases and show excellent safety profiles, but neither preclinical studies nor clinical trials have examined hearing loss as a potential consequence of pharmaceutical HGF activation. Further research is needed to determine the consequences of systemic MM-201 application on the auditory system.
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Affiliation(s)
- Phillip M Uribe
- Department of Integrative Physiology and Neuroscience, Washington State University, 14204 NE Salmon Creek Ave, Vancouver, WA 98686 USA
| | - Alexandria M Hudson
- Department of Integrative Physiology and Neuroscience, Washington State University, 14204 NE Salmon Creek Ave, Vancouver, WA 98686 USA
| | - Gavin Lockard
- Department of Integrative Physiology and Neuroscience, Washington State University, 14204 NE Salmon Creek Ave, Vancouver, WA 98686 USA
| | - Meiyan Jiang
- Oregon Hearing Research Center, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA
| | - Joseph Harding
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, WA 99164 USA
| | - Peter S Steyger
- Translational Hearing Center, Creighton University, Omaha, NE, 68178, USA
| | - Allison B Coffin
- Department of Integrative Physiology and Neuroscience, Washington State University, 14204 NE Salmon Creek Ave, Vancouver, WA 98686 USA.
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20
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Al Aameri RFH, Alanisi EMA, Oluwatosin A, Al Sallami D, Sheth S, Alberts I, Patel S, Rybak LP, Ramkumar V. Targeting CXCL1 chemokine signaling for treating cisplatin ototoxicity. Front Immunol 2023; 14:1125948. [PMID: 37063917 PMCID: PMC10102581 DOI: 10.3389/fimmu.2023.1125948] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2022] [Accepted: 03/17/2023] [Indexed: 04/03/2023] Open
Abstract
Cisplatin is chemotherapy used for solid tumor treatment like lung, bladder, head and neck, ovarian and testicular cancers. However, cisplatin-induced ototoxicity limits the utility of this agent in cancer patients, especially when dose escalations are needed. Ototoxicity is associated with cochlear cell death through DNA damage, the generation of reactive oxygen species (ROS) and the consequent activation of caspase, glutamate excitotoxicity, inflammation, apoptosis and/or necrosis. Previous studies have demonstrated a role of CXC chemokines in cisplatin ototoxicity. In this study, we investigated the role of CXCL1, a cytokine which increased in the serum and cochlea by 24 h following cisplatin administration. Adult male Wistar rats treated with cisplatin demonstrated significant hearing loss, assessed by auditory brainstem responses (ABRs), hair cell loss and loss of ribbon synapse. Immunohistochemical studies evaluated the levels of CXCL1 along with increased presence of CD68 and CD45-positive immune cells in cochlea. Increases in CXCL1 was time-dependent in the spiral ganglion neurons and organ of Corti and was associated with progressive increases in CD45, CD68 and IBA1-positive immune cells. Trans-tympanic administration of SB225002, a chemical inhibitor of CXCR2 (receptor target for CXCL1) reduced immune cell migration, protected against cisplatin-induced hearing loss and preserved hair cell integrity. We show that SB225002 reduced the expression of CXCL1, NOX3, iNOS, TNF-α, IL-6 and COX-2. Similarly, knockdown of CXCR2 by trans-tympanic administration of CXCR2 siRNA protected against hearing loss and loss of outer hair cells and reduced ribbon synapses. In addition, SB225002 reduced the expression of inflammatory mediators induced by cisplatin. These results implicate the CXCL1 chemokine as an early player in cisplatin ototoxicity, possibly by initiating the immune cascade, and indicate that CXCR2 is a relevant target for treating cisplatin ototoxicity.
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Affiliation(s)
- Raheem F. H. Al Aameri
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL, United States
| | - Entkhab M. A. Alanisi
- Department of Pharmaceutical Sciences, Larkin University College of Pharmacy, Miami, FL, United States
| | - Adu Oluwatosin
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL, United States
| | - Dheyaa Al Sallami
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL, United States
| | - Sandeep Sheth
- Department of Pharmaceutical Sciences, Larkin University College of Pharmacy, Miami, FL, United States
| | - Ian Alberts
- Medical Microbiology, Immunology and Cell Biology (MMICB), Southern Illinois University School of Medicine, Springfield, IL, United States
| | - Shree Patel
- Medical Microbiology, Immunology and Cell Biology (MMICB), Southern Illinois University School of Medicine, Springfield, IL, United States
| | - Leonard P. Rybak
- Department of Surgery, Southern Illinois University School of Medicine, Springfield, IL, United States
| | - Vickram Ramkumar
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL, United States
- *Correspondence: Vickram Ramkumar,
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21
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Anastasios G, Magioula G, Konstantinos K, Ioannis A. Noise and Health: Review. Indian J Otolaryngol Head Neck Surg 2022; 74:5482-5491. [PMID: 36742745 PMCID: PMC9895353 DOI: 10.1007/s12070-021-02797-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 08/01/2021] [Indexed: 02/07/2023] Open
Abstract
Noise in human societies is unavoidable, but it tends to become a modern epidemic that induces various detrimental effects to several organs and functions in humans. Increased cardiovascular danger, anxiety and sleep disturbance are just few of these effects. It is noteworthy that children, even neonates and their developing organism are especially vulnerable to noise-related health problems. Noise is measured with special noise-meters. These devices express results in decibels by transforming random noise to a continuous sound. This sound is characterized by equivalent acoustic energy to the random noise for a defined time interval. Human auditory apparatus is principally endangered by acute noises but also by chronic noise exposure, in the context of both occupational and recreational activities. Various mechanisms are implicated in the pathogenesis of noise-induced hearing loss that can cause either temporary or permanent damage. Among them, emphasis is given to the impairment by free radicals and inflammatory mediators, to the activation of apoptotic molecular pathways, but also to glutamate excitotoxicity. A hidden hearing loss, synaptopathy, is attributed to the latter. The irreversible nature of hearing loss, as well as the idiosyncratic sensitivity of individuals, imposes the necessity of early diagnosis of auditory impairment by noise. Super high frequency audiograms, otoacoustic emissions and electrophysiological examinations can address diagnosis. Thankfully, there is extensive research on acoustic trauma therapeutic approaches. However, until we succeed in regenerating the sensory organ of hearing, chronic noise-induced hearing loss cannot be treated. Thus, it is fundamental that society protects people from noise, by laws and regulations.
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Affiliation(s)
- Goulioumis Anastasios
- Department of Otorhinolaryngology, Pediatric Hospital “Karamandanio”, Patras, Greece
| | | | - Kourelis Konstantinos
- Department of Otorhinolaryngology, Pediatric Hospital “Karamandanio”, Patras, Greece
| | - Athanasopoulos Ioannis
- Department of Otorhinolaryngology, Pediatric Center of “Iatriko Athinon” Hospital, Athens, Greece
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22
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Early S, Saad MA, Mallidi S, Mansour A, Seist R, Hasan T, Stankovic KM. A fluorescent photoimmunoconjugate for imaging of cholesteatoma. Sci Rep 2022; 12:19905. [PMID: 36402793 PMCID: PMC9675863 DOI: 10.1038/s41598-022-22072-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Accepted: 10/10/2022] [Indexed: 11/21/2022] Open
Abstract
Cholesteatoma is a potentially serious complication of chronic ear infections and requires surgical intervention for definitive management. Long-term complications include a frequent need for repeat surgical intervention for disease recurrence, and techniques to improve efficacy of single-stage surgery are an important area of continued research. This study investigates a novel application of the photosensitizer immune conjugate (PIC) cetuximab-benzoporphyrin derivative (Cet-BPD) for in vitro localization of human cholesteatoma tissue, coupled with an in vivo safety study for middle ear application of Cet-BPD in a murine model. In fresh human cholesteatoma tissues, Cet-BPD demonstrates selective localization to the hyperplastic squamous cell tissue associated with cholesteatoma, without localizing to other tissues such as middle ear mucosa. Applied to the murine middle ear, Cet-BPD does not demonstrate any deleterious effect on murine hearing when assessed by any of auditory brainstem response (ABR) thresholds, distortion product otoacoustic emission thresholds, or ABR wave I amplitudes. These findings demonstrate the technical promise and encouraging safety profile for the use of PICs for intraoperative localization and treatment of cholesteatoma.
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Affiliation(s)
- Samuel Early
- grid.39479.300000 0000 8800 3003Department of Otolaryngology – Head and Neck Surgery and Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA USA ,grid.38142.3c000000041936754XDepartment of Otolaryngology – Head and Neck Surgery, Harvard Medical School, Boston, MA USA ,grid.413086.80000 0004 0435 1668Department of Otolaryngology – Head and Neck Surgery, University of California San Diego Medical Center, San Diego, CA USA
| | - M. Ahsan Saad
- grid.32224.350000 0004 0386 9924Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA USA
| | - Srivalleesha Mallidi
- grid.32224.350000 0004 0386 9924Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA USA ,grid.429997.80000 0004 1936 7531Department of Biomedical Engineering, Tufts University, Medford, MA USA
| | - Amer Mansour
- grid.39479.300000 0000 8800 3003Department of Otolaryngology – Head and Neck Surgery and Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA USA
| | - Richard Seist
- grid.39479.300000 0000 8800 3003Department of Otolaryngology – Head and Neck Surgery and Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA USA ,grid.38142.3c000000041936754XDepartment of Otolaryngology – Head and Neck Surgery, Harvard Medical School, Boston, MA USA ,grid.168010.e0000000419368956Department of Otolaryngology – Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA USA
| | - Tayyaba Hasan
- grid.32224.350000 0004 0386 9924Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA USA
| | - Konstantina M. Stankovic
- grid.39479.300000 0000 8800 3003Department of Otolaryngology – Head and Neck Surgery and Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA USA ,grid.38142.3c000000041936754XDepartment of Otolaryngology – Head and Neck Surgery, Harvard Medical School, Boston, MA USA ,grid.168010.e0000000419368956Department of Otolaryngology – Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA USA
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23
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Paik CB, Pei M, Oghalai JS. Review of blast noise and the auditory system. Hear Res 2022; 425:108459. [PMID: 35181171 PMCID: PMC9357863 DOI: 10.1016/j.heares.2022.108459] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Revised: 02/03/2022] [Accepted: 02/07/2022] [Indexed: 11/22/2022]
Abstract
The auditory system is particularly vulnerable to blast injury due to the ear's role as a highly sensitive pressure transducer. Over the past several decades, studies have used a variety of animal models and experimental procedures to recreate blast-induced acoustic trauma. Given the developing nature of this field and our incomplete understanding of molecular mechanisms underlying blast-related auditory disturbances, an updated discussion about these studies is warranted. Here, we comprehensively review well-established blast-related auditory pathology including tympanic membrane perforation and hair cell loss. In addition, we discuss important mechanistic studies that aim to bridge gaps in our current understanding of the molecular and microstructural events underlying blast-induced cochlear, auditory nerve, brainstem, and central auditory system damage. Key findings from the recent literature include the association between endolymphatic hydrops and cochlear synaptic loss, blast-induced neuroinflammatory markers in the peripheral and central auditory system, and therapeutic approaches targeting biochemical markers of blast injury. We conclude that blast is an extreme form of noise exposure. Blast waves produce cochlear damage that appears similar to, but more extreme than, the standard noise exposure protocols used in auditory research. However, experimental variations in studies of blast-induced acoustic trauma make it challenging to compare and interpret data across studies.
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Affiliation(s)
- Connie B Paik
- Caruso Department of Otolaryngology-Head and Neck Surgery, Keck School of Medicine of the University of Southern California, Los Angeles, CA USA
| | - Michelle Pei
- Caruso Department of Otolaryngology-Head and Neck Surgery, Keck School of Medicine of the University of Southern California, Los Angeles, CA USA
| | - John S Oghalai
- Caruso Department of Otolaryngology-Head and Neck Surgery, Keck School of Medicine of the University of Southern California, Los Angeles, CA USA.
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24
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Cassinotti LR, Ji L, Borges BC, Cass ND, Desai AS, Kohrman DC, Liberman MC, Corfas G. Cochlear Neurotrophin-3 overexpression at mid-life prevents age-related inner hair cell synaptopathy and slows age-related hearing loss. Aging Cell 2022; 21:e13708. [PMID: 36088647 PMCID: PMC9577954 DOI: 10.1111/acel.13708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Revised: 08/02/2022] [Accepted: 08/21/2022] [Indexed: 01/25/2023] Open
Abstract
Age-related hearing loss (ARHL) is the most prevalent sensory deficit in the elderly. This progressive pathology often has psychological and medical comorbidities, including social isolation, depression, and cognitive decline. Despite ARHL's enormous societal and economic impact, no therapies to prevent or slow its progression exist. Loss of synapses between inner hair cells (IHCs) and spiral ganglion neurons (SGNs), a.k.a. IHC synaptopathy, is an early event in cochlear aging, preceding neuronal and hair cell loss. To determine if age-related IHC synaptopathy can be prevented, and if this impacts the time-course of ARHL, we tested the effects of cochlear overexpression of neurotrophin-3 (Ntf3) starting at middle age. We chose Ntf3 because this neurotrophin regulates the formation of IHC-SGN synapses in the neonatal period. We now show that triggering Ntf3 overexpression by IHC supporting cells starting in middle age rapidly increases the amplitude of sound-evoked neural potentials compared with age-matched controls, indicating that Ntf3 produces a positive effect on cochlear function when the pathology is minimal. Furthermore, near the end of their lifespan, Ntf3-overexpressing mice have milder ARHL, with larger sound-evoked potentials along the ascending auditory pathway and reduced IHC synaptopathy compared with age-matched controls. Our results also provide evidence that an age-related decrease in cochlear Ntf3 expression contributes to ARHL and that Ntf3 supplementation could serve as a therapeutic for this prevalent disorder. Furthermore, these findings suggest that factors that regulate synaptogenesis during development could prevent age-related synaptopathy in the brain, a process involved in several central nervous system degenerative disorders.
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Affiliation(s)
- Luis R. Cassinotti
- Kresge Hearing Research Institute and Department of Otolaryngology‐Head and Neck SurgeryUniversity of MichiganAnn ArborMichiganUSA
| | - Lingchao Ji
- Kresge Hearing Research Institute and Department of Otolaryngology‐Head and Neck SurgeryUniversity of MichiganAnn ArborMichiganUSA
- Present address:
Peking University Shenzhen HospitalShenzhenChina
| | - Beatriz C. Borges
- Kresge Hearing Research Institute and Department of Otolaryngology‐Head and Neck SurgeryUniversity of MichiganAnn ArborMichiganUSA
| | - Nathan D. Cass
- Kresge Hearing Research Institute and Department of Otolaryngology‐Head and Neck SurgeryUniversity of MichiganAnn ArborMichiganUSA
- Present address:
The Otology Group of Vanderbilt, Vanderbilt University Medical Center Department of OtolaryngologyNashvilleTennesseeUSA
| | - Aditi S. Desai
- Kresge Hearing Research Institute and Department of Otolaryngology‐Head and Neck SurgeryUniversity of MichiganAnn ArborMichiganUSA
| | - David C. Kohrman
- Kresge Hearing Research Institute and Department of Otolaryngology‐Head and Neck SurgeryUniversity of MichiganAnn ArborMichiganUSA
| | - M. Charles Liberman
- Eaton‐Peabody Laboratories, Massachusetts Eye & Ear, and Department of Otolaryngology, Head and Neck SurgeryHarvard Medical SchoolBostonMassachusettsUSA
| | - Gabriel Corfas
- Kresge Hearing Research Institute and Department of Otolaryngology‐Head and Neck SurgeryUniversity of MichiganAnn ArborMichiganUSA
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25
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Abstract
PURPOSE OF REVIEW The purpose of this review is to offer a concise summary of current knowledge regarding hidden hearing loss (HHL) and to describe the variety of mechanisms that contribute to its development. We will also discuss the various diagnostic tools that are available as well as future directions. RECENT FINDINGS Hidden hearing loss often also called cochlear synaptopathy affects afferent synapses of the inner hair cells. This description is in contrast to traditional models of hearing loss, which predominantly affects auditory hair cells. In HHL, the synapses of nerve fibres with a slow spontaneous firing rate, which are crucial for locating sound in background noise, are severely impaired. In addition, recent research suggests that HHL may also be related to cochlear nerve demyelination. Noise exposure causes loss of myelin sheath thickness. Auditory brainstem response, envelope-following response and middle-ear muscle reflex are promising diagnostic tests, but they have yet to be validated in humans. SUMMARY Establishing diagnostic tools for cochlear synaptopathy in humans is important to better understand this patient population, predict the long-term outcomes and allow patients to take the necessary protective precautions.
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26
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Valderrama JT, de la Torre A, McAlpine D. The hunt for hidden hearing loss in humans: From preclinical studies to effective interventions. Front Neurosci 2022; 16:1000304. [PMID: 36188462 PMCID: PMC9519997 DOI: 10.3389/fnins.2022.1000304] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Accepted: 08/29/2022] [Indexed: 11/30/2022] Open
Abstract
Many individuals experience hearing problems that are hidden under a normal audiogram. This not only impacts on individual sufferers, but also on clinicians who can offer little in the way of support. Animal studies using invasive methodologies have developed solid evidence for a range of pathologies underlying this hidden hearing loss (HHL), including cochlear synaptopathy, auditory nerve demyelination, elevated central gain, and neural mal-adaptation. Despite progress in pre-clinical models, evidence supporting the existence of HHL in humans remains inconclusive, and clinicians lack any non-invasive biomarkers sensitive to HHL, as well as a standardized protocol to manage hearing problems in the absence of elevated hearing thresholds. Here, we review animal models of HHL as well as the ongoing research for tools with which to diagnose and manage hearing difficulties associated with HHL. We also discuss new research opportunities facilitated by recent methodological tools that may overcome a series of barriers that have hampered meaningful progress in diagnosing and treating of HHL.
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Affiliation(s)
- Joaquin T. Valderrama
- National Acoustic Laboratories, Sydney, NSW, Australia
- Department of Linguistics, Macquarie University Hearing, Macquarie University, Sydney, NSW, Australia
- *Correspondence: Joaquin T. Valderrama, ;
| | - Angel de la Torre
- Department of Signal Theory, Telematics and Communications, University of Granada, Granada, Spain
- Research Centre for Information and Communications Technologies (CITIC-UGR), University of Granada, Granada, Spain
| | - David McAlpine
- Department of Linguistics, Macquarie University Hearing, Macquarie University, Sydney, NSW, Australia
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27
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Toward Personalized Diagnosis and Therapy for Hearing Loss: Insights From Cochlear Implants. Otol Neurotol 2022; 43:e903-e909. [PMID: 35970169 DOI: 10.1097/mao.0000000000003624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
ABSTRACT Sensorineural hearing loss (SNHL) is the most common sensory deficit, disabling nearly half a billion people worldwide. The cochlear implant (CI) has transformed the treatment of patients with SNHL, having restored hearing to more than 800,000 people. The success of CIs has inspired multidisciplinary efforts to address the unmet need for personalized, cellular-level diagnosis, and treatment of patients with SNHL. Current limitations include an inability to safely and accurately image at high resolution and biopsy the inner ear, precluding the use of key structural and molecular information during diagnostic and treatment decisions. Furthermore, there remains a lack of pharmacological therapies for hearing loss, which can partially be attributed to challenges associated with new drug development. We highlight advances in diagnostic and therapeutic strategies for SNHL that will help accelerate the push toward precision medicine. In addition, we discuss technological improvements for the CI that will further enhance its functionality for future patients. This report highlights work that was originally presented by Dr. Stankovic as part of the Dr. John Niparko Memorial Lecture during the 2021 American Cochlear Implant Alliance annual meeting.
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28
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Nguyen TN, Park JS. Intratympanic drug delivery systems to treat inner ear impairments. JOURNAL OF PHARMACEUTICAL INVESTIGATION 2022. [DOI: 10.1007/s40005-022-00586-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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29
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Qi G, Shi L, Qin H, Jiang Q, Guo W, Yu N, Han D, Yang S. Morphology changes in the cochlea of impulse noise-induced hidden hearing loss. Acta Otolaryngol 2022; 142:455-462. [PMID: 35723705 DOI: 10.1080/00016489.2022.2086706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
Abstract
BACKGROUND This study was focused on impulse noise induces hidden hearing loss. OBJECTIVES This study was designed to determine the morphology changes of noise-induced hidden hearing loss (NIHHL). METHOD Fifteen guinea pigs were divided into three groups: noise-induced hidden hearing loss (NIHHL) group, noise-induced hearing loss (NIHL) group, and normal control group. For the NIHHL group, guinea pigs were exposed to 15 times of impulse noise with peak intensity of 163 dB SPL at one time. For the NIHL group, animals were exposed to two rounds of 100 times impulse noise, and the time interval is 24 h. Auditory brain response (ABR) was tested before, immediately, 24 h, one week, and one month after noise exposure to evaluate cochlear physiology changes. One month after noise exposure, all guinea pigs in three groups were sacrificed, and basement membranes were carefully dissected immediately after ABR tests. The cochlea samples were observed by transmission electron microscopy (TEM) to find out the morphology changes. RESULT The ABR results showed that 15 times of impulse noise exposure could cause NIHHL in guinea pigs and 200 times could cause completely hearing loss. Impulse noise exposure could cause a dramatic increase of mitochondria in the inner hair cell. The structures of ribbon synapse and heminode were also obviously impaired compared to the normal group. The nerve fiber and myelin sheath remained intact after impulse noise exposure. CONCLUSION This research revealed that impulse noise could cause hidden hearing loss, and the changes in inner hair cells, ribbon synapse, and heminode all played a vital role in the pathogenesis of hidden hearing loss.
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Affiliation(s)
- Guowei Qi
- Senior Department of Otolaryngology-Head & Neck Surgery, The Sixth Medical Center of PLA General Hospital, National Clinical Research Center for Otolaryngologic Diseases, State Key Lab of Hearing Science, Ministry of Education, Beijing Key Lab of Hearing Impairment Prevention and Treatment Beijing, Beijing, China.,Graduate School of Navy, Medical University Shanghai, Shanghai, China.,Graduate School of Chinese, PLA General Hospital Beijing, Beijing, China
| | - Lei Shi
- Senior Department of Otolaryngology-Head & Neck Surgery, The Sixth Medical Center of PLA General Hospital, National Clinical Research Center for Otolaryngologic Diseases, State Key Lab of Hearing Science, Ministry of Education, Beijing Key Lab of Hearing Impairment Prevention and Treatment Beijing, Beijing, China.,Graduate School of Chinese, PLA General Hospital Beijing, Beijing, China
| | - Handai Qin
- Senior Department of Otolaryngology-Head & Neck Surgery, The Sixth Medical Center of PLA General Hospital, National Clinical Research Center for Otolaryngologic Diseases, State Key Lab of Hearing Science, Ministry of Education, Beijing Key Lab of Hearing Impairment Prevention and Treatment Beijing, Beijing, China.,Graduate School of Chinese, PLA General Hospital Beijing, Beijing, China
| | - Qingqing Jiang
- Senior Department of Otolaryngology-Head & Neck Surgery, The Sixth Medical Center of PLA General Hospital, National Clinical Research Center for Otolaryngologic Diseases, State Key Lab of Hearing Science, Ministry of Education, Beijing Key Lab of Hearing Impairment Prevention and Treatment Beijing, Beijing, China
| | - Weiwei Guo
- Senior Department of Otolaryngology-Head & Neck Surgery, The Sixth Medical Center of PLA General Hospital, National Clinical Research Center for Otolaryngologic Diseases, State Key Lab of Hearing Science, Ministry of Education, Beijing Key Lab of Hearing Impairment Prevention and Treatment Beijing, Beijing, China
| | - Ning Yu
- Senior Department of Otolaryngology-Head & Neck Surgery, The Sixth Medical Center of PLA General Hospital, National Clinical Research Center for Otolaryngologic Diseases, State Key Lab of Hearing Science, Ministry of Education, Beijing Key Lab of Hearing Impairment Prevention and Treatment Beijing, Beijing, China
| | - Dongyi Han
- Senior Department of Otolaryngology-Head & Neck Surgery, The Sixth Medical Center of PLA General Hospital, National Clinical Research Center for Otolaryngologic Diseases, State Key Lab of Hearing Science, Ministry of Education, Beijing Key Lab of Hearing Impairment Prevention and Treatment Beijing, Beijing, China
| | - Shiming Yang
- Senior Department of Otolaryngology-Head & Neck Surgery, The Sixth Medical Center of PLA General Hospital, National Clinical Research Center for Otolaryngologic Diseases, State Key Lab of Hearing Science, Ministry of Education, Beijing Key Lab of Hearing Impairment Prevention and Treatment Beijing, Beijing, China
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30
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Le Prell CG. Prevention of Noise-Induced Hearing Loss Using Investigational Medicines for the Inner Ear: Previous Trial Outcomes Should Inform Future Trial Design. Antioxid Redox Signal 2022; 36:1171-1202. [PMID: 34346254 PMCID: PMC9221155 DOI: 10.1089/ars.2021.0166] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Accepted: 07/25/2021] [Indexed: 11/13/2022]
Abstract
Significance: Noise-induced hearing loss (NIHL) is an important public health issue resulting in decreased quality of life for affected individuals, and significant costs to employers and governmental agencies. Recent Advances: Advances in the mechanistic understanding of NIHL have prompted a growing number of proposed, in-progress, and completed clinical trials for possible protections against NIHL via antioxidants and other drug agents. Thirty-one clinical trials evaluating prevention of either temporary or permanent NIHL were identified and are reviewed. Critical Issues: This review revealed little consistency in the noise-exposed populations in which drugs are evaluated or the primary outcomes used to measure NIHL prevention. Changes in pure-tone thresholds were the most common primary outcomes; specific threshold metrics included both average hearing loss and incidence of significant hearing loss. Changes in otoacoustic emission (OAE) amplitude were relatively common secondary outcomes. Extended high-frequency (EHF) hearing and speech-in-noise perception are commonly adversely affected by noise exposure but are not consistently included in clinical trials assessing prevention of NIHL. Future Directions: Multiple criteria are available for monitoring NIHL, but the specific criterion to be used to define clinically significant otoprotection remains a topic of discussion. Audiogram-based primary outcome measures can be combined with secondary outcomes, including OAE amplitude, EHF hearing, speech-in-noise testing, tinnitus surveys, and patient-reported outcomes. Standardization of test protocols for the above primary and secondary outcomes, and associated reporting criterion for each, would facilitate clinical trial design and comparison of results across investigational drug agents. Antioxid. Redox Signal. 36, 1171-1202.
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Affiliation(s)
- Colleen G. Le Prell
- Department of Speech, Language, and Hearing Science, University of Texas at Dallas, Richardson, Texas, USA
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31
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Foster AC, Szobota S, Piu F, Jacques BE, Moore DR, Sanchez VA, Anderson JJ. A neurotrophic approach to treating hearing loss: Translation from animal models to clinical proof-of-concept. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2022; 151:3937. [PMID: 35778165 DOI: 10.1121/10.0011510] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 05/10/2022] [Indexed: 06/15/2023]
Abstract
Currently, there are no approved medicines available for the treatment of hearing loss. However, research over the past two decades has contributed to a growing understanding of the pathological mechanisms in the cochlea that result in hearing difficulties. The concept that a loss of the synapses connecting inner hair cells with the auditory nerve (cochlear synaptopathy) contributes to hearing loss has gained considerable attention. Both animal and human post-mortem studies support the idea that these synapses (ribbon synapses) are highly vulnerable to noise, ototoxicity, and the aging process. Their degeneration has been suggested as an important factor in the speech-in-noise difficulties commonly experienced by those suffering with hearing loss. Neurotrophins such as brain derived neurotrophic factor (BDNF) have the potential to restore these synapses and provide improved hearing function. OTO-413 is a sustained exposure formulation of BDNF suitable for intratympanic administration that in preclinical models has shown the ability to restore ribbon synapses and provide functional hearing benefit. A phase 1/2 clinical trial with OTO-413 has provided initial proof-of-concept for improved speech-in-noise hearing performance in subjects with hearing loss. Key considerations for the design of this clinical study, including aspects of the speech-in-noise assessments, are discussed.
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Affiliation(s)
- Alan C Foster
- Research and Preclinical Development, Otonomy Inc., 4796 Executive Drive, San Diego, California 92121, USA
| | - Stephanie Szobota
- Research and Preclinical Development, Otonomy Inc., 4796 Executive Drive, San Diego, California 92121, USA
| | - Fabrice Piu
- Research and Preclinical Development, Otonomy Inc., 4796 Executive Drive, San Diego, California 92121, USA
| | - Bonnie E Jacques
- Research and Preclinical Development, Otonomy Inc., 4796 Executive Drive, San Diego, California 92121, USA
| | - David R Moore
- Communication Sciences Research Center, Cincinnati Children's Hospital, 3333 Burnet Avenue, Cincinnati, Ohio 45229-3026, USA
| | - Victoria A Sanchez
- Department of Otolaryngology - Head & Neck Surgery, University of South Florida, 12901 Bruce B. Downs Blvd., MDC 73, Tampa, Florida 33620, USA
| | - Jeffery J Anderson
- Clinical Sciences, Otonomy Inc., 4796 Executive Drive, San Diego, California 92121, USA
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32
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Foster AC, Jacques BE, Piu F. Hearing loss: The final frontier of pharmacology. Pharmacol Res Perspect 2022; 10:e00970. [PMID: 35599339 PMCID: PMC9124819 DOI: 10.1002/prp2.970] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2022] [Accepted: 04/22/2022] [Indexed: 11/25/2022] Open
Abstract
Despite a prevalence greater than cancer or diabetes, there are no currently approved drugs for the treatment of hearing loss. Research over the past two decades has led to a vastly improved understanding of the cellular and molecular mechanisms in the cochlea that lead to hearing deficits and the advent of novel strategies to combat them. Combined with innovative methods that enable local drug delivery to the inner ear, these insights have paved the way for promising therapies that are now under clinical investigation. In this review, we will outline this renaissance of cochlear biology and drug development, focusing on noise, age-related, and chemotherapy-induced hearing dysfunction.
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Ripley S, Xia L, Zhang Z, Aiken SJ, Wang J. Animal-to-Human Translation Difficulties and Problems With Proposed Coding-in-Noise Deficits in Noise-Induced Synaptopathy and Hidden Hearing Loss. Front Neurosci 2022; 16:893542. [PMID: 35720689 PMCID: PMC9199355 DOI: 10.3389/fnins.2022.893542] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 04/22/2022] [Indexed: 12/26/2022] Open
Abstract
Noise induced synaptopathy (NIS) and hidden hearing loss (NIHHL) have been hot topic in hearing research since a massive synaptic loss was identified in CBA mice after a brief noise exposure that did not cause permanent threshold shift (PTS) in 2009. Based upon the amount of synaptic loss and the bias of it to synapses with a group of auditory nerve fibers (ANFs) with low spontaneous rate (LSR), coding-in-noise deficit (CIND) has been speculated as the major difficult of hearing in subjects with NIS and NIHHL. This speculation is based upon the idea that the coding of sound at high level against background noise relies mainly on the LSR ANFs. However, the translation from animal data to humans for NIS remains to be justified due to the difference in noise exposure between laboratory animals and human subjects in real life, the lack of morphological data and reliable functional methods to quantify or estimate the loss of the afferent synapses by noise. Moreover, there is no clear, robust data revealing the CIND even in animals with the synaptic loss but no PTS. In humans, both positive and negative reports are available. The difficulty in verifying CINDs has led a re-examination of the hypothesis that CIND is the major deficit associated with NIS and NIHHL, and the theoretical basis of this idea on the role of LSR ANFs. This review summarized the current status of research in NIS and NIHHL, with focus on the translational difficulty from animal data to human clinicals, the technical difficulties in quantifying NIS in humans, and the problems with the SR theory on signal coding. Temporal fluctuation profile model was discussed as a potential alternative for signal coding at high sound level against background noise, in association with the mechanisms of efferent control on the cochlea gain.
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Affiliation(s)
- Sara Ripley
- School of Communication Sciences and Disorders, Dalhousie University, Halifax, NS, Canada
| | - Li Xia
- Department of Otolaryngology-Head and Neck Surgery, Mianyang Central Hospital, School of Medicine, University of Electronic Science and Technology of China, Mianyang, China
| | - Zhen Zhang
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Jiao Tong University Affiliated Sixth People’s Hospital, Shanghai, China
- Otolaryngology Institute of Shanghai Jiao Tong University, Shanghai, China
| | - Steve J. Aiken
- School of Communication Sciences and Disorders, Dalhousie University, Halifax, NS, Canada
| | - Jian Wang
- School of Communication Sciences and Disorders, Dalhousie University, Halifax, NS, Canada
- Department of Otolaryngology-Head and Neck Surgery, Mianyang Central Hospital, School of Medicine, University of Electronic Science and Technology of China, Mianyang, China
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Suthakar K, Liberman MC. Noise Masking in Cochlear Synaptopathy: Auditory Brainstem Response vs. Auditory Nerve Response in Mouse. J Neurophysiol 2022; 127:1574-1585. [PMID: 35583974 PMCID: PMC9169830 DOI: 10.1152/jn.00402.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 04/28/2022] [Accepted: 05/12/2022] [Indexed: 11/22/2022] Open
Abstract
After acoustic overexposure, many auditory-nerve fiber (ANF) synapses permanently retract from surviving cochlear hair cells. This synaptopathy is hard to diagnose, since it does not elevate audiometric thresholds until almost no synapses remain, nevertheless it may degrade discrimination of complex stimuli especially in noisy environments. Here, we study an assay based on masking the auditory brainstem responses (ABRs) to a moderate-level probe tone with continuous noise of varied sound levels, and we investigate the underlying ANF responses at the single-fiber level. Synaptopathy was induced by overexposure to octave-band noise, resulting in a permanent synaptic loss of ~50%, without permanent threshold elevation except at the highest frequencies. The normal progressive delay of ABR peaks with increasing masker level is diminished in synaptopathic ears; however, the single-fiber analysis suggests that this normal latency shift does not arise because contributing ANFs shift from low-threshold fibers (with high spontaneous rates) to high-threshold fibers (with low spontaneous rates). Rather, it may arise because of a shift in the cochlear region dominating the response. Surprisingly, the dynamic range of masking, i.e. the difference between the lowest masker level that attenuates the ABR to a fixed-level probe and the lowest masker level that eliminates the ABR, is enhanced in the synaptopathic ears. This ABR behavior mirrors the single-fiber data showing a paradoxical enhancement of onset-response synchrony and resistance to masking in responses of ANFs in the synaptopathic regions. An assay based on the dynamic range of masking could be useful in diagnosing synaptic damage in human populations.
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Affiliation(s)
- Kirupa Suthakar
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA, United States
- Department of Otolaryngology, Harvard Medical School, Boston, MA, United States
| | - M Charles Liberman
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA, United States
- Department of Otolaryngology, Harvard Medical School, Boston, MA, United States
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Abstract
INTRODUCTION More than 5% of the world's population have a disabling hearing loss which can be managed by hearing aids or implanted electrical devices. However, outcomes are highly variable, and the sound perceived by recipients is far from perfect. Sparked by the discovery of progenitor cells in the cochlea and rapid progress in drug delivery to the cochlea, biological and pharmaceutical therapies are currently in development to improve the function of the cochlear implant or eliminate the need for it altogether. AREAS COVERED This review highlights progress in emerging regenerative strategies to restore hearing and adjunct therapies to augment the cochlear implant. Novel approaches include the reprogramming of progenitor cells to restore the sensory hair cell population in the cochlea, gene therapy and gene editing to treat hereditary and acquired hearing loss. A detailed review of optogenetics is also presented as a technique that could enable optical stimulation of the spiral ganglion neurons, replacing or complementing electrical stimulation. EXPERT OPINION Increasing evidence of substantial reversal of hearing loss in animal models, alongside rapid advances in delivery strategies to the cochlea and learnings from clinical trials will amalgamate into a biological or pharmaceutical therapy to replace or complement the cochlear implant.
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Affiliation(s)
- Elise Ajay
- Bionics Institute, East Melbourne, Victoria, Australia.,University of Melbourne, Department of Engineering
| | | | - Rachael Richardson
- Bionics Institute, East Melbourne, Victoria, Australia.,University of Melbourne, Medical Bionics Department, Parkville, Victoria, Australia.,University of Melbourne, Department of Surgery (Otolaryngology), East Melbourne, Victoria, Australia
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Efficiency of antioxidant Avenanthramide-C on high-dose methotrexate-induced ototoxicity in mice. PLoS One 2022; 17:e0266108. [PMID: 35353852 PMCID: PMC8967015 DOI: 10.1371/journal.pone.0266108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 03/14/2022] [Indexed: 11/19/2022] Open
Abstract
Methotrexate (MTX) has been used in treating various types of cancers but can also cause damage to normal organs and cell types. Folinic acid (FA) is a well-known MTX antidote that protects against toxicity caused by the drug and has been used for decades. Since hearing loss caused by MTX treatment is not well studied, herein we aimed to investigate the efficiency of the antioxidant Avenanthramide-C (AVN-C) on high-dose MTX (HDMTX) toxicity in the ear and provide insights into the possible mechanism involved in MTX-induced hearing loss in normal adult C57Bl/6 mice and HEI-OC1 cells. Our results show that the levels of MTX increased in the serum and perilymph 30 minutes after systemic administration. MTX increased hearing thresholds in mice, whereas AVN-C and FA preserved hearing within the normal range. MTX also caused a decrease in wave I amplitude, while AVN-C and FA maintained it at higher levels. MTX considerably damaged the cochlear synapses and neuronal integrity, and both AVN-C and FA rescued the synapses. MTX reduced the cell viability and increased the reactive oxygen species (ROS) level in HEI-OC1 cells, but AVN-C and FA reversed these changes. Apoptosis- and ROS-related genes were significantly upregulated in MTX-treated HEI-OC1 cells; however, they were downregulated by AVN-C and FA treatment. We show that MTX can cause severe hearing loss; it can cross the blood–labyrinth barrier and cause damage to the cochlear neurons and outer hair cells (OHCs). The antioxidant AVN-C exerts a strong protective effect against MTX-induced ototoxicity and preserved the inner ear structures (synapses, neurons, and OHCs) from MTX-induced damage. The mechanism of AVN-C against MTX suggests that ROS is involved in HDMTX-induced ototoxicity.
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Gunewardene N, Lam P, Ma Y, Caruso F, Wagstaff S, Richardson RT, Wise AK. Pharmacokinetics and biodistribution of supraparticle-delivered neurotrophin 3 in the guinea pig cochlea. J Control Release 2022; 342:295-307. [PMID: 34999140 DOI: 10.1016/j.jconrel.2021.12.037] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Accepted: 12/29/2021] [Indexed: 02/06/2023]
Abstract
Hearing loss is the most prevalent sensory disorder affecting nearly half a billion people worldwide. Aside from devices to assist hearing, such as hearing aids and cochlear implants, a drug treatment for hearing loss has yet to be developed. The neurotrophin family of growth factors has long been established as a potential therapy, however delivery of these factors into the inner ear at therapeutic levels over a sustained period of time has remained a challenge restricting clinical translation. We previously demonstrated that direct delivery of exogenous neurotrophin-3 (NT3) in the guinea pig cochleae via a bolus injection was rapidly cleared from the inner ear, with almost complete elimination 3 days post-treatment. Here, we explored the potential of suprapaticles (SPs) for NT3 delivery to the inner ear to achieve sustained delivery over time. SPs are porous spheroid structures comprised of smaller colloidal silica nanoparticles that provide a platform for long-term controlled release of therapeutics. This study aimed to assess the pharmacokinetics and biodistribution of SP-delivered NT3. We used a radioactive tracer (iodine 125: 125I) to label the NT3 to determine the loading, retention and distribution of NT3 delivered via SPs. Gamma measurements taken from 125I NT3 loaded SPs revealed high drug loading (an average of 5.3 μg of NT3 loaded per SP weighing 50 μg) and elution capacities in vitro (67% cumulative release over one month). Whole cochlear gamma measurements from SP-implanted cochleae harvested at various time points revealed detection of 125I NT3 in the guinea pig cochlea after one month, with 3.6 and 10% of the loaded drug remaining in the intracochlear and round window-implanted cochleae respectively. Autoradiography analysis of cochlear micro-sections revealed widespread 125I NT3 distribution after intracochlear SP delivery, but more restricted distribution with the round window delivery approach. Collectively, drug delivery into the inner ear using SPs support sustained, long-term availability and release of neurotrophins in the inner ear.
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Affiliation(s)
- Niliksha Gunewardene
- Bionics Institute, Melbourne, Australia; Medical Bionics Department, University of Melbourne, Australia.
| | | | - Yutian Ma
- Bionics Institute, Melbourne, Australia; ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Department of Chemical Engineering, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Frank Caruso
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Department of Chemical Engineering, The University of Melbourne, Parkville, Victoria 3010, Australia
| | | | - Rachael T Richardson
- Bionics Institute, Melbourne, Australia; Medical Bionics Department, University of Melbourne, Australia; Department of Surgery (Otolaryngology), University of Melbourne, Australia
| | - Andrew K Wise
- Bionics Institute, Melbourne, Australia; Medical Bionics Department, University of Melbourne, Australia; Department of Surgery (Otolaryngology), University of Melbourne, Australia.
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Liu W, Johansson Å, Rask-Andersen H, Rask-Andersen M. A combined genome-wide association and molecular study of age-related hearing loss in H. sapiens. BMC Med 2021; 19:302. [PMID: 34847940 PMCID: PMC8638543 DOI: 10.1186/s12916-021-02169-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2021] [Accepted: 10/21/2021] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Sensorineural hearing loss is one of the most common sensory deficiencies. However, the molecular contribution to age-related hearing loss is not fully elucidated. METHODS We performed genome-wide association studies (GWAS) for hearing loss-related traits in the UK Biobank (N = 362,396) and selected a high confidence set of ten hearing-associated gene products for staining in human cochlear samples: EYA4, LMX1A, PTK2/FAK, UBE3B, MMP2, SYNJ2, GRM5, TRIOBP, LMO-7, and NOX4. RESULTS All proteins were found to be expressed in human cochlear structures. Our findings illustrate cochlear structures that mediate mechano-electric transduction of auditory stimuli, neuronal conductance, and neuronal plasticity to be involved in age-related hearing loss. CONCLUSIONS Our results suggest common genetic variation to influence structural resilience to damage as well as cochlear recovery after trauma, which protect against accumulated damage to cochlear structures and the development of hearing loss over time.
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Affiliation(s)
- Wei Liu
- Department of Surgical Sciences, Section of Otorhinolaryngology and Head & Neck Surgery, Uppsala University, SE-751 85, Uppsala, Sweden
| | - Åsa Johansson
- Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Helge Rask-Andersen
- Department of Surgical Sciences, Section of Otorhinolaryngology and Head & Neck Surgery, Uppsala University, SE-751 85, Uppsala, Sweden.
| | - Mathias Rask-Andersen
- Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden.
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Badash I, Quiñones PM, Oghalai KJ, Wang J, Lui CG, Macias-Escriva F, Applegate BE, Oghalai JS. Endolymphatic Hydrops is a Marker of Synaptopathy Following Traumatic Noise Exposure. Front Cell Dev Biol 2021; 9:747870. [PMID: 34805158 PMCID: PMC8602199 DOI: 10.3389/fcell.2021.747870] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Accepted: 10/20/2021] [Indexed: 12/28/2022] Open
Abstract
After acoustic trauma, there can be loss of synaptic connections between inner hair cells and auditory neurons in the cochlea, which may lead to hearing abnormalities including speech-in-noise difficulties, tinnitus, and hyperacusis. We have previously studied mice with blast-induced cochlear synaptopathy and found that they also developed a build-up of endolymph, termed endolymphatic hydrops. In this study, we used optical coherence tomography to measure endolymph volume in live CBA/CaJ mice exposed to various noise intensities. We quantified the number of synaptic ribbons and postsynaptic densities under the inner hair cells 1 week after noise exposure to determine if they correlated with acute changes in endolymph volume measured in the hours after the noise exposure. After 2 h of noise at an intensity of 95 dB SPL or below, both endolymph volume and synaptic counts remained normal. After exposure to 2 h of 100 dB SPL noise, mice developed endolymphatic hydrops and had reduced synaptic counts in the basal and middle regions of the cochlea. Furthermore, round-window application of hypertonic saline reduced the degree of endolymphatic hydrops that developed after 100 dB SPL noise exposure and partially prevented the reduction in synaptic counts in the cochlear base. Taken together, these results indicate that endolymphatic hydrops correlates with noise-induced cochlear synaptopathy, suggesting that these two pathologic findings have a common mechanistic basis.
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Affiliation(s)
- Ido Badash
- Caruso Department of Otolaryngology-Head and Neck Surgery, Keck School of Medicine of the University of Southern California, Los Angeles, CA, United States
| | - Patricia M Quiñones
- Caruso Department of Otolaryngology-Head and Neck Surgery, Keck School of Medicine of the University of Southern California, Los Angeles, CA, United States
| | - Kevin J Oghalai
- Viterbi School of Engineering, University of Southern California, Los Angeles, CA, United States
| | - Juemei Wang
- Caruso Department of Otolaryngology-Head and Neck Surgery, Keck School of Medicine of the University of Southern California, Los Angeles, CA, United States
| | - Christopher G Lui
- Department of Otolaryngology-Head and Neck Surgery, Northwestern University Feinberg School of Medicine, Chicago, IL, United States
| | - Frank Macias-Escriva
- Caruso Department of Otolaryngology-Head and Neck Surgery, Keck School of Medicine of the University of Southern California, Los Angeles, CA, United States
| | - Brian E Applegate
- Caruso Department of Otolaryngology-Head and Neck Surgery, Keck School of Medicine of the University of Southern California, Los Angeles, CA, United States.,Viterbi School of Engineering, University of Southern California, Los Angeles, CA, United States
| | - John S Oghalai
- Caruso Department of Otolaryngology-Head and Neck Surgery, Keck School of Medicine of the University of Southern California, Los Angeles, CA, United States.,Viterbi School of Engineering, University of Southern California, Los Angeles, CA, United States
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40
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Shuster B, Casserly R, Lipford E, Olszewski R, Milon B, Viechweg S, Davidson K, Enoch J, McMurray M, Rutherford MA, Ohlemiller KK, Hoa M, Depireux DA, Mong JA, Hertzano R. Estradiol Protects against Noise-Induced Hearing Loss and Modulates Auditory Physiology in Female Mice. Int J Mol Sci 2021; 22:12208. [PMID: 34830090 PMCID: PMC8620009 DOI: 10.3390/ijms222212208] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 11/05/2021] [Accepted: 11/08/2021] [Indexed: 12/13/2022] Open
Abstract
Recent studies have identified sex-differences in auditory physiology and in the susceptibility to noise-induced hearing loss (NIHL). We hypothesize that 17β-estradiol (E2), a known modulator of auditory physiology, may underpin sex-differences in the response to noise trauma. Here, we gonadectomized B6CBAF1/J mice and used a combination of electrophysiological and histological techniques to study the effects of estrogen replacement on peripheral auditory physiology in the absence of noise exposure and on protection from NIHL. Functional analysis of auditory physiology in gonadectomized female mice revealed that E2-treatment modulated the peripheral response to sound in the absence of changes to the endocochlear potential compared to vehicle-treatment. E2-replacement in gonadectomized female mice protected against hearing loss following permanent threshold shift (PTS)- and temporary threshold shift (TTS)-inducing noise exposures. Histological analysis of the cochlear tissue revealed that E2-replacement mitigated outer hair cell loss and cochlear synaptopathy following noise exposure compared to vehicle-treatment. Lastly, using fluorescent in situ hybridization, we demonstrate co-localization of estrogen receptor-2 with type-1C, high threshold spiral ganglion neurons, suggesting that the observed protection from cochlear synaptopathy may occur through E2-mediated preservation of these neurons. Taken together, these data indicate the estrogen signaling pathways may be harnessed for the prevention and treatment of NIHL.
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Affiliation(s)
- Benjamin Shuster
- Department of Otorhinolaryngology—Head and Neck Surgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (B.S.); (R.C.); (E.L.); (B.M.); (M.M.)
| | - Ryan Casserly
- Department of Otorhinolaryngology—Head and Neck Surgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (B.S.); (R.C.); (E.L.); (B.M.); (M.M.)
| | - Erika Lipford
- Department of Otorhinolaryngology—Head and Neck Surgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (B.S.); (R.C.); (E.L.); (B.M.); (M.M.)
| | - Rafal Olszewski
- Auditory Development and Restoration Program, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, MD 20892, USA; (R.O.); (M.H.)
| | - Béatrice Milon
- Department of Otorhinolaryngology—Head and Neck Surgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (B.S.); (R.C.); (E.L.); (B.M.); (M.M.)
| | - Shaun Viechweg
- Department of Pharmacology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (S.V.); (K.D.); (J.E.); (J.A.M.)
| | - Kanisa Davidson
- Department of Pharmacology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (S.V.); (K.D.); (J.E.); (J.A.M.)
| | - Jennifer Enoch
- Department of Pharmacology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (S.V.); (K.D.); (J.E.); (J.A.M.)
| | - Mark McMurray
- Department of Otorhinolaryngology—Head and Neck Surgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (B.S.); (R.C.); (E.L.); (B.M.); (M.M.)
| | - Mark A. Rutherford
- Department of Otolaryngology, Washington University School of Medicine, St. Louis, MO 63110, USA; (M.A.R.); (K.K.O.)
| | - Kevin K. Ohlemiller
- Department of Otolaryngology, Washington University School of Medicine, St. Louis, MO 63110, USA; (M.A.R.); (K.K.O.)
| | - Michael Hoa
- Auditory Development and Restoration Program, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, MD 20892, USA; (R.O.); (M.H.)
| | | | - Jessica A. Mong
- Department of Pharmacology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (S.V.); (K.D.); (J.E.); (J.A.M.)
| | - Ronna Hertzano
- Department of Otorhinolaryngology—Head and Neck Surgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (B.S.); (R.C.); (E.L.); (B.M.); (M.M.)
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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Chen Z, Huang Y, Yu C, Liu Q, Qiu C, Wan G. Cochlear Sox2 + Glial Cells Are Potent Progenitors for Spiral Ganglion Neuron Reprogramming Induced by Small Molecules. Front Cell Dev Biol 2021; 9:728352. [PMID: 34621745 PMCID: PMC8490772 DOI: 10.3389/fcell.2021.728352] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Accepted: 08/30/2021] [Indexed: 12/13/2022] Open
Abstract
In the mammalian cochlea, spiral ganglion neurons (SGNs) relay the acoustic information to the central auditory circuits. Degeneration of SGNs is a major cause of sensorineural hearing loss and severely affects the effectiveness of cochlear implant therapy. Cochlear glial cells are able to form spheres and differentiate into neurons in vitro. However, the identity of these progenitor cells is elusive, and it is unclear how to differentiate these cells toward functional SGNs. In this study, we found that Sox2+ subpopulation of cochlear glial cells preserves high potency of neuronal differentiation. Interestingly, Sox2 expression was downregulated during neuronal differentiation and Sox2 overexpression paradoxically inhibited neuronal differentiation. Our data suggest that Sox2+ glial cells are potent SGN progenitor cells, a phenotype independent of Sox2 expression. Furthermore, we identified a combination of small molecules that not only promoted neuronal differentiation of Sox2– glial cells, but also removed glial cell identity and promoted the maturation of the induced neurons (iNs) toward SGN fate. In summary, we identified Sox2+ glial subpopulation with high neuronal potency and small molecules inducing neuronal differentiation toward SGNs.
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Affiliation(s)
- Zhen Chen
- MOE Key Laboratory of Model Animal for Disease Study, Department of Otorhinolaryngology Head and Neck Surgery, The Affiliated Drum Tower Hospital of Medical School, Model Animal Research Center of Medical School, Nanjing University, Nanjing, China
| | - Yuhang Huang
- MOE Key Laboratory of Model Animal for Disease Study, Department of Otorhinolaryngology Head and Neck Surgery, The Affiliated Drum Tower Hospital of Medical School, Model Animal Research Center of Medical School, Nanjing University, Nanjing, China
| | - Chaorong Yu
- MOE Key Laboratory of Model Animal for Disease Study, Department of Otorhinolaryngology Head and Neck Surgery, The Affiliated Drum Tower Hospital of Medical School, Model Animal Research Center of Medical School, Nanjing University, Nanjing, China
| | - Qing Liu
- MOE Key Laboratory of Model Animal for Disease Study, Department of Otorhinolaryngology Head and Neck Surgery, The Affiliated Drum Tower Hospital of Medical School, Model Animal Research Center of Medical School, Nanjing University, Nanjing, China
| | - Cui Qiu
- MOE Key Laboratory of Model Animal for Disease Study, Department of Otorhinolaryngology Head and Neck Surgery, The Affiliated Drum Tower Hospital of Medical School, Model Animal Research Center of Medical School, Nanjing University, Nanjing, China
| | - Guoqiang Wan
- MOE Key Laboratory of Model Animal for Disease Study, Department of Otorhinolaryngology Head and Neck Surgery, The Affiliated Drum Tower Hospital of Medical School, Model Animal Research Center of Medical School, Nanjing University, Nanjing, China.,Research Institute of Otolaryngology, Nanjing, China.,Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, Nanjing, China.,Institute for Brain Sciences, Nanjing University, Nanjing, China
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42
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Hosoya M, Fujioka M, Murayama AY, Ozawa H, Okano H, Ogawa K. Neuronal development in the cochlea of a nonhuman primate model, the common marmoset. Dev Neurobiol 2021; 81:905-938. [PMID: 34545999 PMCID: PMC9298346 DOI: 10.1002/dneu.22850] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 08/25/2021] [Accepted: 09/13/2021] [Indexed: 01/02/2023]
Abstract
Precise cochlear neuronal development is vital to hearing ability. Understanding the developmental process of the spiral ganglion is useful for studying hearing loss aimed at aging or regenerative therapy. Although interspecies differences have been reported between rodents and humans, to date, most of our knowledge about the development of cochlear neuronal development has been obtained from rodent models because of the difficulty in using human fetal samples in this field. In this study, we investigated cochlear neuronal development in a small New World monkey species, the common marmoset (Callithrix jacchus). We examined more than 25 genes involved in the neuronal development of the cochlea and described the critical developmental steps of these neurons. We also revealed similarities and differences between previously reported rodent models and this primate animal model. Our results clarified that this animal model of cochlear neuronal development is more similar to humans than rodents and is suitable as an alternative for the analysis of human cochlear development. The time course established in this report will be a useful tool for studying primate‐specific neuronal biology of the inner ear, which could eventually lead to new treatment strategies for human hearing loss.
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Affiliation(s)
- Makoto Hosoya
- Department of Otorhinolaryngology, Head and Neck Surgery, Keio University School of Medicine, Tokyo, Japan
| | - Masato Fujioka
- Department of Otorhinolaryngology, Head and Neck Surgery, Keio University School of Medicine, Tokyo, Japan
| | - Ayako Y Murayama
- Department of Physiology, Keio University School of Medicine, Tokyo, Japan.,Laboratory for Marmoset Neural Architecture, Center for Brain Science, RIKEN, Wako, Japan
| | - Hiroyuki Ozawa
- Department of Otorhinolaryngology, Head and Neck Surgery, Keio University School of Medicine, Tokyo, Japan
| | - Hideyuki Okano
- Department of Physiology, Keio University School of Medicine, Tokyo, Japan.,Laboratory for Marmoset Neural Architecture, Center for Brain Science, RIKEN, Wako, Japan
| | - Kaoru Ogawa
- Department of Otorhinolaryngology, Head and Neck Surgery, Keio University School of Medicine, Tokyo, Japan
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43
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Hickman TT, Hashimoto K, Liberman LD, Liberman MC. Cochlear Synaptic Degeneration and Regeneration After Noise: Effects of Age and Neuronal Subgroup. Front Cell Neurosci 2021; 15:684706. [PMID: 34434091 PMCID: PMC8380781 DOI: 10.3389/fncel.2021.684706] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Accepted: 06/30/2021] [Indexed: 01/24/2023] Open
Abstract
In CBA/CaJ mice, confocal analysis has shown that acoustic overexposure can immediately destroy synapses between auditory-nerve fibers (ANFs) and their peripheral targets, the inner hair cells (IHCs), and that years later, a corresponding number of ANF cell bodies degenerate. In guinea pig, post-exposure disappearance of pre-synaptic ribbons can be equally dramatic, however, post-exposure recovery to near-baseline counts has been reported. Since confocal counts are confounded by thresholding issues, the fall and rise of synaptic ribbon counts could represent “regeneration,” i.e., terminal retraction, re-extension and synaptogenesis, or “recovery,” i.e., down- and subsequent up-regulation of synaptic markers. To clarify, we counted pre-synaptic ribbons, assessed their juxtaposition with post-synaptic receptors, measured the extension of ANF terminals, and quantified the spatial organization and size gradients of these synaptic elements around the hair cell. Present results in guinea pigs exposed as adults (14 months), along with prior results in juveniles (1 month), suggest there is post-exposure neural regeneration in the guinea pig, but not the CBA/CaJ mouse, and that this regenerative capacity extends into adulthood. The results also show, for the first time, that the acute synaptic loss is concentrated on the modiolar side of IHCs, consistent with a selective loss of the high-threshold ANFs with low spontaneous rates. The morphological similarities between the post-exposure neurite extension and synaptogenesis, seen spontaneously in the guinea pig, and in CBA/CaJ only with forced overexpression of neurotrophins, suggest that the key difference may be in the degree of sustained or injury-induced expression of these signaling molecules in the cochlea.
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Affiliation(s)
- Tyler T Hickman
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA, United States.,Department of Otolaryngology-Head and Neck Surgery, Harvard Medical School, Boston, MA, United States
| | - Ken Hashimoto
- Department of Otolaryngology-Head and Neck Surgery, Tohoku University School of Medicine, Sendai, Japan
| | - Leslie D Liberman
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA, United States
| | - M Charles Liberman
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA, United States.,Department of Otolaryngology-Head and Neck Surgery, Harvard Medical School, Boston, MA, United States
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44
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Kempfle JS. Endoscopic-Assisted Drug Delivery for Inner Ear Regeneration. Otolaryngol Clin North Am 2021; 54:189-200. [PMID: 33243375 DOI: 10.1016/j.otc.2020.09.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Sensorineural hearing loss is caused by irreversible loss of auditory hair cells and/or neurons and is increasing in prevalence. Hair cells and neurons do not regenerate after damage, but novel regeneration therapies based on small molecule drugs, gene therapy, and cell replacement strategies offer promising therapeutic options. Endogenous and exogenous regeneration techniques are discussed in context of their feasibility for hair cell and neuron regeneration. Gene therapy and treatment of synaptopathy represent promising future therapies. Minimally invasive endoscopic ear surgery offers a viable approach to aid in delivery of pharmacologic compounds, cells, or viral vectors to the inner ear for all of these techniques.
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Affiliation(s)
- Judith S Kempfle
- Department of Otolaryngology, Massachusetts Eye and Ear Infirmary, Eaton-Peabody Laboratories, C360, 243 Charles Street, Boston, MA 02114, USA.
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45
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Badash I, Applegate BE, Oghalai JS. In Vivo Cochlear imaging provides a tool to study endolymphatic hydrops. J Vestib Res 2021; 31:269-276. [PMID: 33136083 DOI: 10.3233/ves-200718] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Exposure to noise trauma, such as that from improvised explosive devices, can lead to sensorineural hearing loss and a reduced quality of life. In order to elucidate the mechanisms underlying noise-induced hearing loss, we have adapted optical coherence tomography (OCT) for real-time cochlear visualization in live mice after blast exposure. We demonstrated that endolymphatic hydrops develops following blast injury, and that this phenomenon may be associated with glutamate excitotoxicity and cochlear synaptopathy. Additionally, osmotic stabilization of endolymphatic hydrops partially rescues cochlear synapses after blast trauma. OCT is thus a valuable research tool for investigating the mechanisms underlying acoustic trauma and dynamic changes in endolymph volume. It may also help with the diagnosis and treatment of human hearing loss and/or vertigo in the near future.
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Affiliation(s)
- Ido Badash
- Caruso Department of Otolaryngology-Head and Neck Surgery, University of Southern California, Los Angeles, CA, USA
| | - Brian E Applegate
- Caruso Department of Otolaryngology-Head and Neck Surgery, University of Southern California, Los Angeles, CA, USA
| | - John S Oghalai
- Caruso Department of Otolaryngology-Head and Neck Surgery, University of Southern California, Los Angeles, CA, USA
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46
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Middle Ear Muscle Reflex and Word Recognition in "Normal-Hearing" Adults: Evidence for Cochlear Synaptopathy? Ear Hear 2021; 41:25-38. [PMID: 31584501 DOI: 10.1097/aud.0000000000000804] [Citation(s) in RCA: 58] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES Permanent threshold elevation after noise exposure, ototoxic drugs, or aging is caused by loss of sensory cells; however, animal studies show that hair cell loss is often preceded by degeneration of synapses between sensory cells and auditory nerve fibers. The silencing of these neurons, especially those with high thresholds and low spontaneous rates, degrades auditory processing and may contribute to difficulties in understanding speech in noise. Although cochlear synaptopathy can be diagnosed in animals by measuring suprathreshold auditory brainstem responses, its diagnosis in humans remains a challenge. In mice, cochlear synaptopathy is also correlated with measures of middle ear muscle (MEM) reflex strength, possibly because the missing high-threshold neurons are important drivers of this reflex. The authors hypothesized that measures of the MEM reflex might be better than other assays of peripheral function in predicting difficulties hearing in difficult listening environments in human subjects. DESIGN The authors recruited 165 normal-hearing healthy subjects, between 18 and 63 years of age, with no history of ear or hearing problems, no history of neurologic disorders, and unremarkable otoscopic examinations. Word recognition in quiet and in difficult listening situations was measured in four ways: using isolated words from the Northwestern University auditory test number six corpus with either (a) 0 dB signal to noise, (b) 45% time compression with reverberation, or (c) 65% time compression with reverberation, and (d) with a modified version of the QuickSIN. Audiometric thresholds were assessed at standard and extended high frequencies. Outer hair cell function was assessed by distortion product otoacoustic emissions (DPOAEs). Middle ear function and reflexes were assessed using three methods: the acoustic reflex threshold as measured clinically, wideband tympanometry as measured clinically, and a custom wideband method that uses a pair of click probes flanking an ipsilateral noise elicitor. Other aspects of peripheral auditory function were assessed by measuring click-evoked gross potentials, that is, summating potential (SP) and action potential (AP) from ear canal electrodes. RESULTS After adjusting for age and sex, word recognition scores were uncorrelated with audiometric or DPOAE thresholds, at either standard or extended high frequencies. MEM reflex thresholds were significantly correlated with scores on isolated word recognition, but not with the modified version of the QuickSIN. The highest pairwise correlations were seen using the custom assay. AP measures were correlated with some of the word scores, but not as highly as seen for the MEM custom assay, and only if amplitude was measured from SP peak to AP peak, rather than baseline to AP peak. The highest pairwise correlations with word scores, on all four tests, were seen with the SP/AP ratio, followed closely by SP itself. When all predictor variables were combined in a stepwise multivariate regression, SP/AP dominated models for all four word score outcomes. MEM measures only enhanced the adjusted r values for the 45% time compression test. The only other predictors that enhanced model performance (and only for two outcome measures) were measures of interaural threshold asymmetry. CONCLUSIONS Results suggest that, among normal-hearing subjects, there is a significant peripheral contribution to diminished hearing performance in difficult listening environments that is not captured by either threshold audiometry or DPOAEs. The significant univariate correlations between word scores and either SP/AP, SP, MEM reflex thresholds, or AP amplitudes (in that order) are consistent with a type of primary neural degeneration. However, interpretation is clouded by uncertainty as to the mix of pre- and postsynaptic contributions to the click-evoked SP. None of the assays presented here has the sensitivity to diagnose neural degeneration on a case-by-case basis; however, these tests may be useful in longitudinal studies to track accumulation of neural degeneration in individual subjects.
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47
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Jeffers PWC, Bourien J, Diuba A, Puel JL, Kujawa SG. Noise-Induced Hearing Loss in Gerbil: Round Window Assays of Synapse Loss. Front Cell Neurosci 2021; 15:699978. [PMID: 34385909 PMCID: PMC8354318 DOI: 10.3389/fncel.2021.699978] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2021] [Accepted: 07/05/2021] [Indexed: 01/31/2023] Open
Abstract
Previous work in animals with recovered hearing thresholds but permanent inner hair cell synapse loss after noise have suggested initial vulnerability of low spontaneous rate (SR) auditory nerve fibers (ANF). As these fibers have properties of response that facilitate robust sound coding in continuous noise backgrounds, their targeted loss would have important implications for function. To address the issue of relative ANF vulnerabilities after noise, we assessed cochlear physiologic and histologic consequences of temporary threshold shift-producing sound over-exposure in the gerbil, a species with well-characterized distributions of auditory neurons by SR category. The noise exposure targeted a cochlear region with distributed innervation (low-, medium- and high-SR neurons). It produced moderate elevations in outer hair cell-based distortion-product otoacoustic emission and whole nerve compound action potential thresholds in this region, with accompanying reductions in suprathreshold response amplitudes, quantified at 24 h. These parameters of response recovered well with post-exposure time. Chronic synapse loss was maximum in the frequency region initially targeted by the noise. Cochlear round window recorded mass potentials (spontaneous neural noise and sound-driven peri-stimulus time responses, PSTR) reflected parameters of the loss not detected by the conventional assays. Spontaneous activity was acutely reduced. Steady-state (PSTR plateau) activity was correlated with synapse loss in frequency regions with high concentrations of low-SR neurons, whereas the PSTR onset peak and spontaneous round window noise, both dominated by high-SR fiber activity, were relatively unaltered across frequency in chronic ears. Together, results suggest that acute targets of noise were of mixed SR subtypes, but chronic targets were predominantly low-SR neurons. PSTRs captured key properties of the auditory nerve response and vulnerability to injury that should yield important diagnostic information in hearing loss etiologies producing cochlear synaptic and neural loss.
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Affiliation(s)
- Penelope W C Jeffers
- Program in Speech and Hearing Bioscience and Technology, Harvard University, Boston, MA, United States.,Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA, United States
| | - Jérôme Bourien
- Institute for Neurosciences of Montpellier, University of Montpellier, INSERM, Montpellier, France
| | - Artem Diuba
- Institute for Neurosciences of Montpellier, University of Montpellier, INSERM, Montpellier, France
| | - Jean-Luc Puel
- Institute for Neurosciences of Montpellier, University of Montpellier, INSERM, Montpellier, France
| | - Sharon G Kujawa
- Program in Speech and Hearing Bioscience and Technology, Harvard University, Boston, MA, United States.,Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA, United States.,Department of Otolaryngology-Head and Neck Surgery, Harvard Medical School, Boston, MA, United States
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48
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Szeto B, Valentini C, Aksit A, Werth EG, Goeta S, Brown LM, Olson ES, Kysar JW, Lalwani AK. Impact of Systemic versus Intratympanic Dexamethasone Administration on the Perilymph Proteome. J Proteome Res 2021; 20:4001-4009. [PMID: 34291951 DOI: 10.1021/acs.jproteome.1c00322] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Glucocorticoids are the first-line treatment for sensorineural hearing loss, but little is known about the mechanism of their protective effect or the impact of route of administration. The recent development of hollow microneedles enables safe and reliable sampling of perilymph for proteomic analysis. Using these microneedles, we investigate the effect of intratympanic (IT) versus intraperitoneal (IP) dexamethasone administration on guinea pig perilymph proteome. Guinea pigs were treated with IT dexamethasone (n = 6), IP dexamethasone (n = 8), or untreated for control (n = 8) 6 h prior to aspiration. The round window membrane (RWM) was accessed via a postauricular approach, and hollow microneedles were used to perforate the RWM and aspirate 1 μL of perilymph. Perilymph samples were analyzed by liquid chromatography-mass spectrometry-based label-free quantitative proteomics. Mass spectrometry raw data files have been deposited in an international public repository (MassIVE proteomics repository at https://massive.ucsd.edu/) under data set # MSV000086887. In the 22 samples of perilymph analyzed, 632 proteins were detected, including the inner ear protein cochlin, a perilymph marker. Of these, 14 proteins were modulated by IP, and three proteins were modulated by IT dexamethasone. In both IP and IT dexamethasone groups, VGF nerve growth factor inducible was significantly upregulated compared to control. The remaining adjusted proteins modulate neurons, inflammation, or protein synthesis. Proteome analysis facilitated by the use of hollow microneedles shows that route of dexamethasone administration impacts changes seen in perilymph proteome. Compared to IT administration, the IP route was associated with greater changes in protein expression, including proteins involved in neuroprotection, inflammatory pathway, and protein synthesis. Our findings show that microneedles can mediate safe and effective intracochlear sampling and hold promise for inner ear diagnostics.
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Affiliation(s)
- Betsy Szeto
- Department of Otolaryngology-Head and Neck Surgery, Columbia University Vagelos College of Physicians and Surgeons, New York, New York 10032, United States
| | - Chris Valentini
- Department of Otolaryngology-Head and Neck Surgery, Columbia University Vagelos College of Physicians and Surgeons, New York, New York 10032, United States
| | - Aykut Aksit
- Department of Mechanical Engineering, Columbia University, New York, New York 10027, United States
| | - Emily G Werth
- Quantitative Proteomics and Metabolomics Center, Department of Biological Sciences, Columbia University, New York, New York 10027, United States
| | - Shahar Goeta
- Quantitative Proteomics and Metabolomics Center, Department of Biological Sciences, Columbia University, New York, New York 10027, United States
| | - Lewis M Brown
- Quantitative Proteomics and Metabolomics Center, Department of Biological Sciences, Columbia University, New York, New York 10027, United States
| | - Elizabeth S Olson
- Department of Otolaryngology-Head and Neck Surgery, Columbia University Vagelos College of Physicians and Surgeons, New York, New York 10032, United States.,Department of Biomedical Engineering, Columbia University, New York, New York 10027, United States
| | - Jeffrey W Kysar
- Department of Otolaryngology-Head and Neck Surgery, Columbia University Vagelos College of Physicians and Surgeons, New York, New York 10032, United States.,Department of Mechanical Engineering, Columbia University, New York, New York 10027, United States
| | - Anil K Lalwani
- Department of Otolaryngology-Head and Neck Surgery, Columbia University Vagelos College of Physicians and Surgeons, New York, New York 10032, United States.,Department of Mechanical Engineering, Columbia University, New York, New York 10027, United States
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49
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Kimura E, Mizutari K, Kurioka T, Kawauchi S, Satoh Y, Sato S, Shiotani A. Effect of shock wave power spectrum on the inner ear pathophysiology in blast-induced hearing loss. Sci Rep 2021; 11:14704. [PMID: 34282183 PMCID: PMC8289960 DOI: 10.1038/s41598-021-94080-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 06/29/2021] [Indexed: 11/10/2022] Open
Abstract
Blast exposure can induce various types of hearing impairment, including permanent hearing loss, tinnitus, and hyperacusis. Herein, we conducted a detailed investigation of the cochlear pathophysiology in blast-induced hearing loss in mice using two blasts with different characteristics: a low-frequency dominant blast generated by a shock tube and a high-frequency dominant shock wave generated by laser irradiation (laser-induced shock wave). The pattern of sensorineural hearing loss (SNHL) was low-frequency- and high-frequency-dominant in response to the low- and high-frequency blasts, respectively. Pathological examination revealed that cochlear synaptopathy was the most frequent cochlear pathology after blast exposure, which involved synapse loss in the inner hair cells without hair cell loss, depending on the power spectrum of the blast. This pathological change completely reflected the physiological analysis of wave I amplitude using auditory brainstem responses. Stereociliary bundle disruption in the outer hair cells was also dependent on the blast’s power spectrum. Therefore, we demonstrated that the dominant frequency of the blast power spectrum was the principal factor determining the region of cochlear damage. We believe that the presenting models would be valuable both in blast research and the investigation of various types of hearing loss whose pathogenesis involves cochlear synaptopathy.
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Affiliation(s)
- Eiko Kimura
- Department of Otolaryngology-Head and Neck Surgery, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama, 359-8513, Japan
| | - Kunio Mizutari
- Department of Otolaryngology-Head and Neck Surgery, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama, 359-8513, Japan.
| | - Takaomi Kurioka
- Department of Otolaryngology-Head and Neck Surgery, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama, 359-8513, Japan
| | - Satoko Kawauchi
- Division of Bioinformation and Therapeutic Systems, National Defense Medical College Research Institute, Saitama, 359-8513, Japan
| | - Yasushi Satoh
- Department of Biochemistry, National Defense Medical College, Saitama, 359-8513, Japan
| | - Shunichi Sato
- Division of Bioinformation and Therapeutic Systems, National Defense Medical College Research Institute, Saitama, 359-8513, Japan
| | - Akihiro Shiotani
- Department of Otolaryngology-Head and Neck Surgery, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama, 359-8513, Japan
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50
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Kempfle JS, Duro MV, Zhang A, Amador CD, Kuang R, Lu R, Kashemirov BA, Edge AS, McKenna CE, Jung DH. A Novel Small Molecule Neurotrophin-3 Analogue Promotes Inner Ear Neurite Outgrowth and Synaptogenesis In vitro. Front Cell Neurosci 2021; 15:666706. [PMID: 34335184 PMCID: PMC8319950 DOI: 10.3389/fncel.2021.666706] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Accepted: 06/18/2021] [Indexed: 11/15/2022] Open
Abstract
Sensorineural hearing loss is irreversible and is associated with the loss of spiral ganglion neurons (SGNs) and sensory hair cells within the inner ear. Improving spiral ganglion neuron (SGN) survival, neurite outgrowth, and synaptogenesis could lead to significant gains for hearing-impaired patients. There has therefore been intense interest in the use of neurotrophic factors in the inner ear to promote both survival of SGNs and re-wiring of sensory hair cells by surviving SGNs. Neurotrophin-3 (NT-3) and brain-derived neurotrophic factor (BDNF) represent the primary neurotrophins in the inner ear during development and throughout adulthood, and have demonstrated potential for SGN survival and neurite outgrowth. We have pioneered a hybrid molecule approach to maximize SGN stimulation in vivo, in which small molecule analogues of neurotrophins are linked to bisphosphonates, which in turn bind to cochlear bone. We have previously shown that a small molecule BDNF analogue coupled to risedronate binds to bone matrix and promotes SGN neurite outgrowth and synaptogenesis in vitro. Because NT-3 has been shown in a variety of contexts to have a greater regenerative capacity in the cochlea than BDNF, we sought to develop a similar approach for NT-3. 1Aa is a small molecule analogue of NT-3 that has been shown to activate cells through TrkC, the NT-3 receptor, although its activity on SGNs has not previously been described. Herein we describe the design and synthesis of 1Aa and a covalent conjugate of 1Aa with risedronate, Ris-1Aa. We demonstrate that both 1Aa and Ris-1Aa stimulate neurite outgrowth in SGN cultures at a significantly higher level compared to controls. Ris-1Aa maintained its neurotrophic activity when bound to hydroxyapatite, the primary mineral component of bone. Both 1Aa and Ris-1Aa promote significant synaptic regeneration in cochlear explant cultures, and both 1Aa and Ris-1Aa appear to act at least partly through TrkC. Our results provide the first evidence that a small molecule analogue of NT-3 can stimulate SGNs and promote regeneration of synapses between SGNs and inner hair cells. Our findings support the promise of hydroxyapatite-targeting bisphosphonate conjugation as a novel strategy to deliver neurotrophic agents to SGNs encased within cochlear bone.
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Affiliation(s)
- Judith S Kempfle
- Department of Otolaryngology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA, United States.,Department of Otolaryngology, University Medical Center Tübingen, Tübingen, Germany
| | - Marlon V Duro
- Department of Chemistry, University of Southern California, Los Angeles, CA, United States
| | - Andrea Zhang
- Department of Otolaryngology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA, United States
| | - Carolina D Amador
- Department of Chemistry, University of Southern California, Los Angeles, CA, United States
| | - Richard Kuang
- Department of Otolaryngology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA, United States
| | - Ryan Lu
- Department of Otolaryngology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA, United States
| | - Boris A Kashemirov
- Department of Chemistry, University of Southern California, Los Angeles, CA, United States
| | - Albert S Edge
- Department of Otolaryngology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA, United States
| | - Charles E McKenna
- Department of Chemistry, University of Southern California, Los Angeles, CA, United States
| | - David H Jung
- Department of Otolaryngology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA, United States
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