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Arambula AM, Gu S, Warnecke A, Schmitt HA, Staecker H, Hoa M. In Silico Localization of Perilymph Proteins Enriched in Meńier̀e Disease Using Mammalian Cochlear Single-cell Transcriptomics. OTOLOGY & NEUROTOLOGY OPEN 2023; 3:e027. [PMID: 38516320 PMCID: PMC10950140 DOI: 10.1097/ono.0000000000000027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 12/01/2022] [Indexed: 03/23/2024]
Abstract
Hypothesis Proteins enriched in the perilymph proteome of Meńier̀e disease (MD) patients may identify affected cell types. Utilizing single-cell transcriptome datasets from the mammalian cochlea, we hypothesize that these enriched perilymph proteins can be localized to specific cochlear cell types. Background The limited understanding of human inner ear pathologies and their associated biomolecular variations hinder efforts to develop disease-specific diagnostics and therapeutics. Perilymph sampling and analysis is now enabling further characterization of the cochlear microenvironment. Recently, enriched inner ear protein expression has been demonstrated in patients with MD compared to patients with other inner ear diseases. Localizing expression of these proteins to cochlear cell types can further our knowledge of potential disease pathways and subsequent development of targeted therapeutics. Methods We compiled previously published data regarding differential perilymph proteome profiles amongst patients with MD, otosclerosis, enlarged vestibular aqueduct, sudden hearing loss, and hearing loss of undefined etiology (controls). Enriched proteins in MD were cross-referenced against published single-cell/single-nucleus RNA-sequencing datasets to localize gene expression to specific cochlear cell types. Results In silico analysis of single-cell transcriptomic datasets demonstrates enrichment of a unique group of perilymph proteins associated with MD in a variety of intracochlear cells, and some exogeneous hematologic and immune effector cells. This suggests that these cell types may play an important role in the pathology associated with late MD, suggesting potential future areas of investigation for MD pathophysiology and treatment. Conclusions Perilymph proteins enriched in MD are expressed by specific cochlear cell types based on in silico localization, potentially facilitating development of disease-specific diagnostic markers and therapeutics.
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Affiliation(s)
- Alexandra M. Arambula
- Department of Otolaryngology-Head & Neck Surgery, University of Kansas Medical Center, Kansas City, KS
| | - Shoujun Gu
- Auditory Development and Restoration Program, National Institute on Deafness and Other Communication Disorders, Bethesda, MD
| | - Athanasia Warnecke
- Department of Otolaryngology and Cluster of Excellence of the German Research Foundation (DFG; “Deutsche Forschungsgemeinschaft”) “Hearing4all,” Hannover Medical School, Hannover, Germany
| | - Heike A. Schmitt
- Department of Otolaryngology and Cluster of Excellence of the German Research Foundation (DFG; “Deutsche Forschungsgemeinschaft”) “Hearing4all,” Hannover Medical School, Hannover, Germany
| | - Hinrich Staecker
- Department of Otolaryngology-Head & Neck Surgery, University of Kansas Medical Center, Kansas City, KS
| | - Michael Hoa
- Auditory Development and Restoration Program, National Institute on Deafness and Other Communication Disorders, Bethesda, MD
- Department of Otolaryngology–Head and Neck Surgery, Georgetown University Medical Center, Washington, DC
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Liu W, Chen H, Zhu X, Yu H. Expression of Calbindin-D28K in the Developing and Adult Mouse Cochlea. J Histochem Cytochem 2022; 70:583-596. [PMID: 35975307 PMCID: PMC9393511 DOI: 10.1369/00221554221119543] [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: 11/22/2022] Open
Abstract
Herein, we aimed to use double-labeling immunofluorescence to describe the expression pattern of Calbindin-D28K (CaBP28K) in the mouse cochlea from late embryonic (E) stages to the adulthood. CaBP28K was expressed in the inner hair cells (IHCs) and the greater epithelial ridge (GER) at E17. In addition, its expression was observed in the interdental cells. On postnatal day 1 (P1), CaBP28K immunoreactivity was observed in the IHCs and outer hair cells (OHCs) and was also specifically expressed in the nucleus and the cytoplasm of spiral ganglion neurons (SGNs). At P8, CaBP28K labeling disappeared from the interdental cells, and the CaBP28K-positive domain within the GER shifted from the entire cytoplasm to only the apical and basal regions. At P14, CaBP28K immunoreactivity was lost from the GER; however, its expression in the IHCs and OHCs, as well as the SGNs, persisted into adulthood. The identification of CaBP28K in the hair cells (HCs) and cuticular plates, as well as SGNs, was confirmed by its colocalization with several markers for Sox2, Myosin VIIa, Phalloidin, and Tuj1. We also detected colocalization with calmodulin in the cytoplasm of both HCs and SGNs. Western blot revealed an increase in CaBP28K postnatal expression in the mouse cochlea.
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Affiliation(s)
- Wenjing Liu
- Department of Otorhinolaryngology-Head and Neck Surgery, Zhongda Hospital, Southeast University, Nanjing, China
| | - Huijun Chen
- Department of Otorhinolaryngology-Head and Neck Surgery, Zhongda Hospital, Southeast University, Nanjing, China
| | - Xin Zhu
- Department of Otorhinolaryngology-Head and Neck Surgery, Zhongda Hospital, Southeast University, Nanjing, China
| | - Hao Yu
- Anhui Province Key Laboratory of Biological Macro-Molecules Research, Wannan Medical College, Wuhu, China
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Wang SQ, Li CL, Xu JQ, Chen LL, Xie YZ, Dai PD, Ren LJ, Yao WJ, Zhang TY. The Effect of Endolymphatic Hydrops and Mannitol Dehydration Treatment on Guinea Pigs. Front Cell Neurosci 2022; 16:836093. [PMID: 35480960 PMCID: PMC9035551 DOI: 10.3389/fncel.2022.836093] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 02/24/2022] [Indexed: 01/14/2023] Open
Abstract
Background Endolymphatic hydrops (EH) is considered as the pathological correlate of Menière’s disease (MD) and cause of hearing loss. The mechanism of EH, remaining unrevealed, poses challenges for formalized clinical trials. Objective This study aims to investigate the development of hearing loss, as well as the effect of dehydration treatment on EH animal models. Methods In this study, different severity EH animal models were created. The laser Doppler vibrometer (LDV) and auditory brainstem responses (ABR) were used to study the effects of EH and the dehydration effects of mannitol. The LDV was used to measure the vibration of the round window membrane (RWM) reflecting the changes in inner ear impedance. ABR was used to evaluate the hearing changes. Furthermore, tissue section and scanning electron microscopy (SEM) observations were used to analyze the anatomical change to the cochlea and outer hair cells. Results The RWM vibrations decreased with the severity of EH, indicating an increase in the cochlear impedance. The dehydration therapy lowered the impedance to restore acoustic transduction in EH 10- and 20-day animal models. Simultaneously, the ABR thresholds increased in EH models and were restored after dehydration. Moreover, a difference in the hearing was found between ABR and LDV results in severe EH animal models, and the dehydration therapy was less effective, indicating a sensorineural hearing loss (SNHL). Conclusion Endolymphatic hydrops causes hearing loss by increasing the cochlear impedance in all tested groups, and mannitol dehydration is an effective therapy to restore hearing. However, SNHL occurs for the EH 30-day animal models, limiting the effectiveness of dehydration. Our results suggest the use of dehydrating agents in the early stage of EH.
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Affiliation(s)
- Shu-Qi Wang
- Department of Facial Plastic Reconstruction Surgery, Eye and ENT Hospital of Fudan University, Shanghai, China
- ENT Institute, Eye and ENT Hospital of Fudan University, Shanghai, China
| | - Chen-Long Li
- Department of Facial Plastic Reconstruction Surgery, Eye and ENT Hospital of Fudan University, Shanghai, China
- ENT Institute, Eye and ENT Hospital of Fudan University, Shanghai, China
- Hearing Medicine Key Laboratory, National Health Commission of China, Shanghai, China
| | - Jing-Qi Xu
- Department of Facial Plastic Reconstruction Surgery, Eye and ENT Hospital of Fudan University, Shanghai, China
- ENT Institute, Eye and ENT Hospital of Fudan University, Shanghai, China
| | - Li-Li Chen
- Department of Facial Plastic Reconstruction Surgery, Eye and ENT Hospital of Fudan University, Shanghai, China
- ENT Institute, Eye and ENT Hospital of Fudan University, Shanghai, China
- Hearing Medicine Key Laboratory, National Health Commission of China, Shanghai, China
| | - You-Zhou Xie
- Department of Facial Plastic Reconstruction Surgery, Eye and ENT Hospital of Fudan University, Shanghai, China
- ENT Institute, Eye and ENT Hospital of Fudan University, Shanghai, China
- Hearing Medicine Key Laboratory, National Health Commission of China, Shanghai, China
| | - Pei-Dong Dai
- Department of Facial Plastic Reconstruction Surgery, Eye and ENT Hospital of Fudan University, Shanghai, China
- ENT Institute, Eye and ENT Hospital of Fudan University, Shanghai, China
| | - Liu-Jie Ren
- Department of Facial Plastic Reconstruction Surgery, Eye and ENT Hospital of Fudan University, Shanghai, China
- ENT Institute, Eye and ENT Hospital of Fudan University, Shanghai, China
- Hearing Medicine Key Laboratory, National Health Commission of China, Shanghai, China
- *Correspondence: Liu-Jie Ren,
| | - Wen-Juan Yao
- School of Mechanics and Engineering Science, Shanghai University, Shanghai, China
- Shanghai Institute of Applied Mathematics and Mechanics, Shanghai, China
- Wen-Juan Yao,
| | - Tian-Yu Zhang
- Department of Facial Plastic Reconstruction Surgery, Eye and ENT Hospital of Fudan University, Shanghai, China
- ENT Institute, Eye and ENT Hospital of Fudan University, Shanghai, China
- Hearing Medicine Key Laboratory, National Health Commission of China, Shanghai, China
- Tian-Yu Zhang,
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Lefler SM, Duncan RK, Goodman SS, Guinan JJ, Lichtenhan JT. Measurements From Ears With Endolymphatic Hydrops and 2-Hydroxypropyl-Beta-Cyclodextrin Provide Evidence That Loudness Recruitment Can Have a Cochlear Origin. Front Surg 2021; 8:687490. [PMID: 34676239 PMCID: PMC8523923 DOI: 10.3389/fsurg.2021.687490] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 09/02/2021] [Indexed: 11/21/2022] Open
Abstract
Background: Loudness recruitment is commonly experienced by patients with putative endolymphatic hydrops. Loudness recruitment is abnormal loudness growth with high-level sounds being perceived as having normal loudness even though hearing thresholds are elevated. The traditional interpretation of recruitment is that cochlear amplification has been reduced. Since the cochlear amplifier acts primarily at low sound levels, an ear with elevated thresholds from reduced cochlear amplification can have normal processing at high sound levels. In humans, recruitment can be studied using perceptual loudness but in animals physiological measurements are used. Recruitment in animal auditory-nerve responses has never been unequivocally demonstrated because the animals used had damage to sensory and neural cells, not solely a reduction of cochlear amplification. Investigators have thus looked for, and found, evidence of recruitment in the auditory central nervous system (CNS). While studies on CNS recruitment are informative, they cannot rule out the traditional interpretation of recruitment originating in the cochlea. Design: We used techniques that could assess hearing function throughout entire frequency- and dynamic-range of hearing. Measurements were made from two animal models: guinea-pig ears with endolymphatic-sac-ablation surgery to produce endolymphatic hydrops, and naïve guinea-pig ears with cochlear perfusions of 13 mM 2-Hydroxypropyl-Beta-Cyclodextrin (HPBCD) in artificial perilymph. Endolymphatic sac ablation caused low-frequency loss. Animals treated with HPBCD had hearing loss at all frequencies. None of these animals had loss of hair cells or synapses on auditory nerve fibers. Results: In ears with endolymphatic hydrops and those perfused with HPBCD, auditory-nerve based measurements at low frequencies showed recruitment compared to controls. Recruitment was not found at high frequencies (> 4 kHz) where hearing thresholds were normal in ears with endolymphatic hydrops and elevated in ears treated with HPBCD. Conclusions: We found compelling evidence of recruitment in auditory-nerve data. Such clear evidence has never been shown before. Our findings suggest that, in patients suspected of having endolymphatic hydrops, loudness recruitment may be a good indication that the associated low-frequency hearing loss originates from a reduction of cochlear amplification, and that measurements of recruitment could be used in differential diagnosis and treatment monitoring of Ménière's disease.
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Affiliation(s)
- Shannon M Lefler
- Department of Otolaryngology, Washington University School of Medicine in St. Louis, Saint Louis, MO, United States
| | - Robert K Duncan
- Department of Otolaryngology-Head and Neck Surgery, Kresge Hearing Research Institute, University of Michigan, Ann Arbor, MI, United States
| | - Shawn S Goodman
- Department of Communication Sciences and Disorders, University of Iowa, Iowa City, IA, United States
| | - John J Guinan
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA, United States.,Department of Otolaryngology, Harvard Medical School, Boston, MA, United States
| | - Jeffery T Lichtenhan
- Department of Otolaryngology, Washington University School of Medicine in St. Louis, Saint Louis, MO, United States
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Beck-Nielsen SS, Mughal Z, Haffner D, Nilsson O, Levtchenko E, Ariceta G, de Lucas Collantes C, Schnabel D, Jandhyala R, Mäkitie O. FGF23 and its role in X-linked hypophosphatemia-related morbidity. Orphanet J Rare Dis 2019; 14:58. [PMID: 30808384 PMCID: PMC6390548 DOI: 10.1186/s13023-019-1014-8] [Citation(s) in RCA: 132] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Accepted: 01/30/2019] [Indexed: 12/29/2022] Open
Abstract
Background X-linked hypophosphatemia (XLH) is an inherited disease of phosphate metabolism in which inactivating mutations of the Phosphate Regulating Endopeptidase Homolog, X-Linked (PHEX) gene lead to local and systemic effects including impaired growth, rickets, osteomalacia, bone abnormalities, bone pain, spontaneous dental abscesses, hearing difficulties, enthesopathy, osteoarthritis, and muscular dysfunction. Patients with XLH present with elevated levels of fibroblast growth factor 23 (FGF23), which is thought to mediate many of the aforementioned manifestations of the disease. Elevated FGF23 has also been observed in many other diseases of hypophosphatemia, and a range of animal models have been developed to study these diseases, yet the role of FGF23 in the pathophysiology of XLH is incompletely understood. Methods The role of FGF23 in the pathophysiology of XLH is here reviewed by describing what is known about phenotypes associated with various PHEX mutations, animal models of XLH, and non-nutritional diseases of hypophosphatemia, and by presenting molecular pathways that have been proposed to contribute to manifestations of XLH. Results The pathophysiology of XLH is complex, involving a range of molecular pathways that variously contribute to different manifestations of the disease. Hypophosphatemia due to elevated FGF23 is the most obvious contributor, however localised fluctuations in tissue non-specific alkaline phosphatase (TNAP), pyrophosphate, calcitriol and direct effects of FGF23 have been observed to be associated with certain manifestations. Conclusions By describing what is known about these pathways, this review highlights key areas for future research that would contribute to the understanding and clinical treatment of non-nutritional diseases of hypophosphatemia, particularly XLH.
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Affiliation(s)
| | - Zulf Mughal
- Royal Manchester Children's Hospital, Manchester, UK
| | | | - Ola Nilsson
- Karolinska Institutet, Stockholm, Sweden and Örebro University, Örebro, Sweden
| | | | - Gema Ariceta
- Hospital Universitario Materno-Infantil Vall d'Hebron, Universitat Autonoma de Barcelona, Barcelona, Spain
| | | | - Dirk Schnabel
- University Children's Hospital of Berlin, Berlin, Germany
| | | | - Outi Mäkitie
- Children's Hospital, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
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Kim J, Xia A, Grillet N, Applegate BE, Oghalai JS. Osmotic stabilization prevents cochlear synaptopathy after blast trauma. Proc Natl Acad Sci U S A 2018; 115:E4853-E4860. [PMID: 29735658 PMCID: PMC6003510 DOI: 10.1073/pnas.1720121115] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Traumatic noise causes hearing loss by damaging sensory hair cells and their auditory synapses. There are no treatments. Here, we investigated mice exposed to a blast wave approximating a roadside bomb. In vivo cochlear imaging revealed an increase in the volume of endolymph, the fluid within scala media, termed endolymphatic hydrops. Endolymphatic hydrops, hair cell loss, and cochlear synaptopathy were initiated by trauma to the mechanosensitive hair cell stereocilia and were K+-dependent. Increasing the osmolality of the adjacent perilymph treated endolymphatic hydrops and prevented synaptopathy, but did not prevent hair cell loss. Conversely, inducing endolymphatic hydrops in control mice by lowering perilymph osmolality caused cochlear synaptopathy that was glutamate-dependent, but did not cause hair cell loss. Thus, endolymphatic hydrops is a surrogate marker for synaptic bouton swelling after hair cells release excitotoxic levels of glutamate. Because osmotic stabilization prevents neural damage, it is a potential treatment to reduce hearing loss after noise exposure.
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Affiliation(s)
- Jinkyung Kim
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, Stanford, CA 94305
| | - Anping Xia
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, Stanford, CA 94305
| | - Nicolas Grillet
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, Stanford, CA 94305
| | - Brian E Applegate
- Department of Biomedical Engineering, Texas A&M University, College Station, TX 77843
| | - John S Oghalai
- Caruso Department of Otolaryngology-Head and Neck Surgery, University of Southern California, Los Angeles, CA 90033
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The Intimate Relationship between Vestibular Migraine and Meniere Disease: A Review of Pathogenesis and Presentation. Behav Neurol 2016; 2016:3182735. [PMID: 27651559 PMCID: PMC5019886 DOI: 10.1155/2016/3182735] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2016] [Accepted: 08/07/2016] [Indexed: 11/30/2022] Open
Abstract
Vestibular migraine (VM) has only recently been recognized as a distinct disease entity. One reason is that its symptoms overlap greatly with those of other vestibular disorders, especially Meniere disease (MD). The pathophysiology of neither VM nor MD is entirely elucidated. However, there are many theories linking migraine to both disorders. We reviewed the current understanding of migraine, VM, and MD and described how VM and MD are similar or different from each other in terms of pathophysiology and presentation, including hypotheses that the two share a common etiology and/or are variants of the same disease.
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Electrophysiological detection of scalar changing perimodiolar cochlear electrode arrays: a long term follow-up study. Eur Arch Otorhinolaryngol 2016; 273:4251-4256. [DOI: 10.1007/s00405-016-4175-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 06/24/2016] [Indexed: 10/21/2022]
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Wick CC, Semaan MT, Zheng QY, Megerian CA. A Genetic Murine Model of Endolymphatic Hydrops: The Phex Mouse. CURRENT OTORHINOLARYNGOLOGY REPORTS 2014; 2:144-151. [PMID: 25309828 PMCID: PMC4193546 DOI: 10.1007/s40136-014-0048-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Animal models of endolymphatic hydrops (ELH) provide critical insight into the pathophysiology of Meniere's disease (MD). A new genetic murine model, called the Phex mouse, circumvents prior need for a time and cost-intensive surgical procedure to create ELH. The Phex mouse model of ELH, which also has X-linked hypophosphatemic rickets, creates a postnatal, spontaneous, and progressive ELH whose phenotype has a predictable decline of vestibular and hearing function reminiscent of human MD. The Phex mouse enables real-time histopathologic analysis to assess diagnostic and therapeutic interventions as well as further our understanding of ELH's adverse effects. Already the model has validated electrocochleography and cervical vestibular evoked myogenic potential as useful diagnostic tools. New data on caspase activity in apoptosis of the spiral ganglion neurons may help target future therapeutic interventions. This paper highlights the development of the Phex mouse model and highlights its role in characterizing ELH.
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Affiliation(s)
- Cameron C Wick
- Ear, Nose, and Throat Institute, University Hospitals Case Medical Center, Case Western Reserve University, 11100 Euclid Avenue, Cleveland, OH 44106, USA
| | - Maroun T Semaan
- Ear, Nose, and Throat Institute, University Hospitals Case Medical Center, Case Western Reserve University, 11100 Euclid Avenue, Cleveland, OH 44106, USA
| | - Qing Yin Zheng
- Ear, Nose, and Throat Institute, University Hospitals Case Medical Center, Case Western Reserve University, 11100 Euclid Avenue, Cleveland, OH 44106, USA
| | - Cliff A Megerian
- Ear, Nose, and Throat Institute, University Hospitals Case Medical Center, Case Western Reserve University, 11100 Euclid Avenue, Cleveland, OH 44106, USA
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Semaan MT, Zheng QY, Han F, Zheng Y, Yu H, Heaphy JC, Megerian CA. Characterization of neuronal cell death in the spiral ganglia of a mouse model of endolymphatic hydrops. Otol Neurotol 2013; 34:559-69. [PMID: 23462289 PMCID: PMC3628741 DOI: 10.1097/mao.0b013e3182868312] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
HYPOTHESIS Spiral ganglion neurons (SGN) in the Phex male mouse, a murine model of postnatal endolymphatic hydrops (ELH) undergo progressive deterioration reminiscent of human and other animal models of ELH with features suggesting apoptosis as an important mechanism. BACKGROUND Histologic analysis of the mutant's cochlea demonstrates ELH by postnatal Day (P) 21 and SGN loss by P90. The SGN loss seems to occur in a consistent topographic pattern beginning at the cochlear apex. METHODS SGN were counted at P60, P90, and P120. Semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR), quantitative PCR, and immunohistochemical analyses of activated caspase-3, caspase-8, and caspase-9 were performed on cochlear sections obtained from mutants and controls. Terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling assay (TUNEL) was carried out on 2 mutants and 2 controls. RESULTS Corrected SGN counts in control mice were greater in the apical turn of the cochleae at P90 and P120, respectively (p < 0.01). Increased expression of activated caspase-3, caspase-8, and caspase-9 was seen in the mutant. At later time points, activated caspase expression gradually declined in the apical turns and increased in basal turns of the cochlea. Quantitative and semiquantitative PCR analysis confirmed increased expression of caspase-3, caspase-8, and caspase-9 at P21 and P40. TUNEL staining demonstrated apoptosis at P90 in the apical and basal turns of the mutant cochleae. CONCLUSION SGN degeneration in the Phex /Y mouse seems to mimic patterns observed in other animals with ELH. Apoptosis plays an important role in the degeneration of the SGN in the Phex male mouse.
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Affiliation(s)
- Maroun T Semaan
- Department of Otolaryngology-Head and Neck Surgery, University Hospitals Case Medical Center, Cleveland, Ohio 44106, USA.
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Momin SR, Melki SJ, Obokhare JO, Fares SA, Semaan MT, Megerian CA. Hearing preservation in Guinea pigs with long-standing endolymphatic hydrops. Otol Neurotol 2011; 32:1583-9. [PMID: 22015942 PMCID: PMC3220888 DOI: 10.1097/mao.0b013e3182382a64] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
HYPOTHESIS Interruption of the excitotoxic and inflammatory pathways implicated in endolymphatic hydrops (ELH)-associated hearing loss (HL) should afford hearing protection at the neuronal level. BACKGROUND Previous work in our laboratory in the mouse model of ELH shows that dimethyl sulfoxide (DMSO), an anti-inflammatory solvent, can slow the progression of HL before neuronal degeneration occurs. Riluzole, a glutamate release inhibitor, may provide synergistic benefit. This study was designed to quantify the effects of DMSO and riluzole in a long-term model. METHODS Guinea pigs with surgically induced ELH were sorted into 3 groups: riluzole+DMSO (Group 1), DMSO alone (Group 2), and untreated controls (Group 3). Animals in Groups 1 and 2 received daily injections of the study drug(s). All animals underwent auditory-evoked brainstem response evaluation every 4 weeks until 24 weeks, when they were sacrificed. Cochleae were preserved; spiral ganglion density was quantified. Animals without hydrops were excluded from the study as surgical failures. RESULTS Animals from all groups developed unilateral HL. At the end of the experiment, HL was significantly lower in Group 1 relative to Group 3 (p = 0.049) and trended toward lower in Group 2 relative to Group 3 (p = 0.097). Groups 1 and 2 were not different (p = 0.311). At the cellular level, there is no evidence of neuronal degeneration in either treated group, whereas there is a significant neuronal degeneration in the untreated group. CONCLUSION These results confirm the hearing protection observed with DMSO in short-term studies. However, unlike the previous study, which showed no additive benefit to riluzole, the combined treatment group in this study showed a hearing-protective effect at 24 weeks. This indicates a potential additive benefit conferred by riluzole toward long-term hearing protection. The study also finds evidence of statistically significant neuronal protection with both treatment groups. Overall, study provides additional evidence that DMSO and riluzole may preserve or slow the long-term progression of ELH-associated HL.
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Affiliation(s)
- Suhael R. Momin
- Department of Otolaryngology-Head and Neck Surgery, University Hospitals Case Medical Center
| | - Sami J. Melki
- Department of Otolaryngology-Head and Neck Surgery, University Hospitals Case Medical Center
| | - Joy O. Obokhare
- Department of Otolaryngology-Head and Neck Surgery, University Hospitals Case Medical Center
| | - Souha A. Fares
- Department of Biostatistics and Epidemiology, Case Western Reserve University Cleveland, Ohio
| | - Maroun T. Semaan
- Department of Otolaryngology-Head and Neck Surgery, University Hospitals Case Medical Center
| | - Cliff A. Megerian
- Department of Otolaryngology-Head and Neck Surgery, University Hospitals Case Medical Center
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