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Chai Y, He W, Yang W, Hetrick AP, Gonzalez JG, Sargsyan L, Wu H, Jung TTK, Li H. Intratympanic Lipopolysaccharide Elevates Systemic Fluorescent Gentamicin Uptake in the Cochlea. Laryngoscope 2021; 131:E2573-E2582. [PMID: 33956344 PMCID: PMC8453712 DOI: 10.1002/lary.29610] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 04/09/2021] [Accepted: 04/26/2021] [Indexed: 12/20/2022]
Abstract
Objectives/Hypothesis Lipopolysaccharide (LPS), a key component of bacterial endotoxins, activates macrophages and triggers the release of inflammatory cytokines in mammalian tissues. Recent studies have shown that intratympanic injection of LPS simulates acute otitis media (AOM) and results in morphological and functional changes in the inner ear. Here we established an AOM mouse model with LPS to investigate the uptake of ototoxic gentamicin in the inner ear, and elucidated the underlying mechanism by focusing on cochlear inflammation as a result of AOM. Study Design Preclinical rodent animal model. Methods Fluorescently tagged gentamicin (GTTR) was systemically administered to mice with AOM. Iba1‐positive macrophage morphology and inner ear cytokine profile were evaluated by immunofluorescence technique and a mouse cytokine array kit, respectively. Results We observed characteristic symptoms of AOM in the LPS‐treated ears with elevated hearing thresholds indicating a conductive hearing loss. More importantly, the LPS‐induced AOM activated cochlear inflammatory responses, manifested by macrophage infiltration, particularly in the organ of Corti and the spiral ligament, in addition to the up‐regulation of proinflammatory cytokines. Meanwhile, GTTR uptake in the stria vascularis and sensory hair cells from all the LPS‐treated ears was significantly enhanced at 24, 48, and 72‐hour post‐treatment, as the most prominent enhancement was observed in the 48‐hour group. Conclusion In summary, this study suggests that the pathological cochlea is more susceptible to ototoxic drugs, including aminoglycosides, and justified the clinical concern of aminoglycoside ototoxicity in the AOM treatment. Laryngoscope, 131:E2573–E2582, 2021
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Affiliation(s)
- Yongchuan Chai
- Research Service, VA Loma Linda Healthcare System, Loma Linda, California, U.S.A.,Department of Otolaryngology Head and Neck Surgery, Shanghai Ninth People's Hospital Affiliated Shanghai Jiaotong University School of Medicine, Shanghai, China.,Ear Institute, Shanghai Jiaotong University School of Medicine, Shanghai, China.,Department of Otolaryngology Head and Neck Surgery, Loma Linda University Health, Loma Linda, California, U.S.A
| | - Weiwei He
- Research Service, VA Loma Linda Healthcare System, Loma Linda, California, U.S.A.,Department of Otolaryngology Head and Neck Surgery, Shanghai Ninth People's Hospital Affiliated Shanghai Jiaotong University School of Medicine, Shanghai, China.,Ear Institute, Shanghai Jiaotong University School of Medicine, Shanghai, China.,Department of Otolaryngology Head and Neck Surgery, Loma Linda University Health, Loma Linda, California, U.S.A
| | - Weiqiang Yang
- Research Service, VA Loma Linda Healthcare System, Loma Linda, California, U.S.A.,Department of Otolaryngology Head and Neck Surgery, Loma Linda University Health, Loma Linda, California, U.S.A
| | - Alisa P Hetrick
- Research Service, VA Loma Linda Healthcare System, Loma Linda, California, U.S.A
| | - Jessica G Gonzalez
- Research Service, VA Loma Linda Healthcare System, Loma Linda, California, U.S.A
| | - Liana Sargsyan
- Research Service, VA Loma Linda Healthcare System, Loma Linda, California, U.S.A
| | - Hao Wu
- Department of Otolaryngology Head and Neck Surgery, Shanghai Ninth People's Hospital Affiliated Shanghai Jiaotong University School of Medicine, Shanghai, China.,Ear Institute, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Timothy T K Jung
- Research Service, VA Loma Linda Healthcare System, Loma Linda, California, U.S.A.,Department of Otolaryngology Head and Neck Surgery, Loma Linda University Health, Loma Linda, California, U.S.A
| | - Hongzhe Li
- Research Service, VA Loma Linda Healthcare System, Loma Linda, California, U.S.A.,Department of Otolaryngology Head and Neck Surgery, Loma Linda University Health, Loma Linda, California, U.S.A
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2
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Qian X, He Z, Wang Y, Chen B, Hetrick A, Dai C, Chi F, Li H, Ren D. Hair cell uptake of gentamicin in the developing mouse utricle. J Cell Physiol 2020; 236:5235-5252. [PMID: 33368220 DOI: 10.1002/jcp.30228] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 11/27/2020] [Accepted: 12/08/2020] [Indexed: 12/27/2022]
Abstract
Intratympanic injection of gentamicin has proven to be an effective therapy for intractable vestibular dysfunction. However, most studies to date have focused on the cochlea, so little is known about the distribution and uptake of gentamicin by the counterpart of the auditory system, specifically vestibular hair cells (HCs). Here, with a combination of in vivo and in vitro approaches, we used a gentamicin-Texas Red (GTTR) conjugate to investigate the mechanisms of gentamicin vestibulotoxicity in the developing mammalian utricular HCs. In vivo, GTTR fluorescence was concentrated in the apical cytoplasm and the cellular membrane of neonatal utricular HCs, but scarce in the nucleus of HCs and supporting cells. Quantitative analysis showed the GTTR uptake by striolar HCs was significantly higher than that in the extrastriola. In addition, the GTTR fluorescence intensity in the striola was increased gradually from 1 to 8 days, peaking at 8-9 days postnatally. In vitro, utricle explants were incubated with GTTR and candidate uptake conduits, including mechanotransduction (MET) channels and endocytosis in the HC, were inhibited separately. GTTR uptake by HCs could be inhibited by quinine, a blocker of MET channels, under both normal and stressed conditions. Meanwhile, endocytic inhibition only reduced GTTR uptake in the CoCl2 hypoxia model. In sum, the maturation of MET channels mediated uptake of GTTR into vestibular HCs. Under stressed conditions, MET channels play a pronounced role, manifested by channel-dependent stress enhanced GTTR permeation, while endocytosis participates in GTTR entry in a more selective manner.
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Affiliation(s)
- Xiaoqing Qian
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital, Fudan University, Shanghai, China.,NHC Key Laboratory of Hearing Medicine (Fudan University), Shanghai, China
| | - Ziyu He
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital, Fudan University, Shanghai, China.,NHC Key Laboratory of Hearing Medicine (Fudan University), Shanghai, China
| | - Yanmei Wang
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital, Fudan University, Shanghai, China.,NHC Key Laboratory of Hearing Medicine (Fudan University), Shanghai, China
| | - Binjun Chen
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital, Fudan University, Shanghai, China.,NHC Key Laboratory of Hearing Medicine (Fudan University), Shanghai, China
| | - Alisa Hetrick
- Research Service, VA Loma Linda Healthcare System, Loma Linda, California, USA
| | - Chunfu Dai
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital, Fudan University, Shanghai, China.,NHC Key Laboratory of Hearing Medicine (Fudan University), Shanghai, China
| | - Fanglu Chi
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital, Fudan University, Shanghai, China.,NHC Key Laboratory of Hearing Medicine (Fudan University), Shanghai, China
| | - Hongzhe Li
- Research Service, VA Loma Linda Healthcare System, Loma Linda, California, USA.,Department of Otolaryngology-Head and Neck Surgery, Loma Linda University School of Medicine, Loma Linda, California, USA
| | - Dongdong Ren
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital, Fudan University, Shanghai, China.,NHC Key Laboratory of Hearing Medicine (Fudan University), Shanghai, China
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3
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Nyberg S, Abbott NJ, Shi X, Steyger PS, Dabdoub A. Delivery of therapeutics to the inner ear: The challenge of the blood-labyrinth barrier. Sci Transl Med 2020; 11:11/482/eaao0935. [PMID: 30842313 DOI: 10.1126/scitranslmed.aao0935] [Citation(s) in RCA: 157] [Impact Index Per Article: 39.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Revised: 12/01/2017] [Accepted: 03/22/2018] [Indexed: 12/20/2022]
Abstract
Permanent hearing loss affects more than 5% of the world's population, yet there are no nondevice therapies that can protect or restore hearing. Delivery of therapeutics to the cochlea and vestibular system of the inner ear is complicated by their inaccessible location. Drug delivery to the inner ear via the vasculature is an attractive noninvasive strategy, yet the blood-labyrinth barrier at the luminal surface of inner ear capillaries restricts entry of most blood-borne compounds into inner ear tissues. Here, we compare the blood-labyrinth barrier to the blood-brain barrier, discuss invasive intratympanic and intracochlear drug delivery methods, and evaluate noninvasive strategies for drug delivery to the inner ear.
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Affiliation(s)
- Sophie Nyberg
- Biological Sciences, Sunnybrook Research Institute, Toronto, ON M4N 3M5, Canada
| | - N Joan Abbott
- Institute of Pharmaceutical Science, King's College London, London SE1 9NH, UK
| | - Xiaorui Shi
- Oregon Hearing Research Center, Department of Otolaryngology, Head & Neck Surgery, Oregon Health & Science University, Portland, OR 97239, USA
| | - Peter S Steyger
- Oregon Hearing Research Center, Department of Otolaryngology, Head & Neck Surgery, Oregon Health & Science University, Portland, OR 97239, USA
| | - Alain Dabdoub
- Biological Sciences, Sunnybrook Research Institute, Toronto, ON M4N 3M5, Canada. .,Department of Otolaryngology-Head & Neck Surgery, University of Toronto, Toronto, ON M5G 2C4, Canada.,Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON M5G 2C4, Canada
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4
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Lesus J, Arias K, Kulaga J, Sobkiv S, Patel A, Babu V, Kambalyal A, Patel M, Padron F, Mozaffari P, Jayakumar A, Ghatalah L, Laban N, Bahari R, Perkins G, Lysakowski A. Why study inner ear hair cell mitochondria? HNO 2019; 67:429-433. [PMID: 30969353 DOI: 10.1007/s00106-019-0662-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
In several systems of the body (muscle, liver, nerves), new studies have examined the internal structure of mitochondria and brought to light striking new findings about how mitochondria are constructed and how their structure affects cell function. In the inner ear field, however, we have little structural knowledge about hair cell and supporting cell mitochondria, and virtually none about mitochondrial subtypes or how they function in health and disease. The need for such knowledge is discussed in this short review.
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Affiliation(s)
- J Lesus
- Dept. of Anatomy and Cell Biology, University of Illinois at Chicago, 808 S. Wood St., M/C 512, 60612, Chicago, IL, USA
| | - K Arias
- Dept. of Biological Sciences, University of Illinois at Chicago, Chicago, IL, USA
| | - J Kulaga
- Dept. of Anatomy and Cell Biology, University of Illinois at Chicago, 808 S. Wood St., M/C 512, 60612, Chicago, IL, USA
| | - S Sobkiv
- Dept. of Biological Sciences, University of Illinois at Chicago, Chicago, IL, USA
| | - A Patel
- Dept. of Anatomy and Cell Biology, University of Illinois at Chicago, 808 S. Wood St., M/C 512, 60612, Chicago, IL, USA
| | - V Babu
- Dept. of Biological Sciences, University of Illinois at Chicago, Chicago, IL, USA
| | - A Kambalyal
- Dept. of Economics, University of Illinois at Chicago, Chicago, IL, USA
| | - M Patel
- Dept. of Biological Sciences, University of Illinois at Chicago, Chicago, IL, USA
| | - F Padron
- Dept. of Biological Sciences, University of Illinois at Chicago, Chicago, IL, USA
| | - P Mozaffari
- Dept. of Economics, University of Illinois at Chicago, Chicago, IL, USA
| | - A Jayakumar
- Dept. of Biological Sciences, University of Illinois at Chicago, Chicago, IL, USA
| | - L Ghatalah
- Dept. of Biological Sciences, University of Illinois at Chicago, Chicago, IL, USA
| | - N Laban
- Dept. of Biological Sciences, University of Illinois at Chicago, Chicago, IL, USA
| | - R Bahari
- Dept. of Biological Sciences, University of Illinois at Chicago, Chicago, IL, USA
| | - G Perkins
- National Center for Microscopy and Imaging Research (NCMIR), University of California, San Diego, La Jolla, CA, USA
| | - A Lysakowski
- Dept. of Anatomy and Cell Biology, University of Illinois at Chicago, 808 S. Wood St., M/C 512, 60612, Chicago, IL, USA. .,Dept. of Otolaryngology, University of Illinois at Chicago, Chicago, IL, USA.
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5
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Jiang M, Taghizadeh F, Steyger PS. Potential Mechanisms Underlying Inflammation-Enhanced Aminoglycoside-Induced Cochleotoxicity. Front Cell Neurosci 2017; 11:362. [PMID: 29209174 PMCID: PMC5702304 DOI: 10.3389/fncel.2017.00362] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 11/03/2017] [Indexed: 12/20/2022] Open
Abstract
Aminoglycoside antibiotics remain widely used for urgent clinical treatment of life-threatening infections, despite the well-recognized risk of permanent hearing loss, i.e., cochleotoxicity. Recent studies show that aminoglycoside-induced cochleotoxicity is exacerbated by bacteriogenic-induced inflammation. This implies that those with severe bacterial infections (that induce systemic inflammation), and are treated with bactericidal aminoglycosides are at greater risk of drug-induced hearing loss than previously recognized. Incorporating this novel comorbid factor into cochleotoxicity risk prediction models will better predict which individuals are more predisposed to drug-induced hearing loss. Here, we review the cellular and/or signaling mechanisms by which host-mediated inflammatory responses to infection could enhance the trafficking of systemically administered aminoglycosides into the cochlea to enhance the degree of cochleotoxicity over that in healthy preclinical models. Once verified, these mechanisms will be potential targets for novel pharmacotherapeutics that reduce the risk of drug-induced hearing loss (and acute kidney damage) without compromising the life-saving bactericidal efficacy of aminoglycosides.
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Affiliation(s)
- Meiyan Jiang
- Oregon Hearing Research Center, Oregon Health & Science University, Portland, OR, United States
| | - Farshid Taghizadeh
- Oregon Hearing Research Center, Oregon Health & Science University, Portland, OR, United States
| | - Peter S Steyger
- Oregon Hearing Research Center, Oregon Health & Science University, Portland, OR, United States.,National Center for Rehabilitative Auditory Research, VA Portland Health Care System, Portland, OR, United States
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Garinis AC, Kemph A, Tharpe AM, Weitkamp JH, McEvoy C, Steyger PS. Monitoring neonates for ototoxicity. Int J Audiol 2017; 57:S41-S48. [PMID: 28949262 DOI: 10.1080/14992027.2017.1339130] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
OBJECTIVES Neonates admitted to the neonatal intensive care unit (NICU) are at greater risk of permanent hearing loss compared to infants in well mother and baby units. Several factors have been associated with this increased prevalence of hearing loss, including congenital infections (e.g. cytomegalovirus or syphilis), ototoxic drugs (such as aminoglycoside or glycopeptide antibiotics), low birth weight, hypoxia and length of stay. The aetiology of this increased prevalence of hearing loss remains poorly understood. DESIGN Here we review current practice and discuss the feasibility of designing improved ototoxicity screening and monitoring protocols to better identify acquired, drug-induced hearing loss in NICU neonates. STUDY SAMPLE A review of published literature. CONCLUSIONS We conclude that current audiological screening or monitoring protocols for neonates are not designed to adequately detect early onset of ototoxicity. This paper offers a detailed review of evidence-based research, and offers recommendations for developing and implementing an ototoxicity monitoring protocol for young infants, before and after discharge from the hospital.
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Affiliation(s)
- Angela C Garinis
- a Oregon Hearing Research Center, Otolaryngology , Oregon Health & Science University , Portland , OR , USA.,b National Center for Rehabilitative Auditory Research , VA Portland Health Care System , Portland , OR , USA
| | - Alison Kemph
- c Hearing and Speech Sciences , Vanderbilt University School of Medicine , Nashville , TN , USA
| | - Anne Marie Tharpe
- c Hearing and Speech Sciences , Vanderbilt University School of Medicine , Nashville , TN , USA
| | | | - Cynthia McEvoy
- e Neonatology, Pediatrics , Oregon Health & Science University , Portland , OR , USA
| | - Peter S Steyger
- a Oregon Hearing Research Center, Otolaryngology , Oregon Health & Science University , Portland , OR , USA.,b National Center for Rehabilitative Auditory Research , VA Portland Health Care System , Portland , OR , USA
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7
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Garinis AC, Liao S, Cross CP, Galati J, Middaugh JL, Mace JC, Wood AM, McEvoy L, Moneta L, Lubianski T, Coopersmith N, Vigo N, Hart C, Riddle A, Ettinger O, Nold C, Durham H, MacArthur C, McEvoy C, Steyger PS. Effect of gentamicin and levels of ambient sound on hearing screening outcomes in the neonatal intensive care unit: A pilot study. Int J Pediatr Otorhinolaryngol 2017; 97:42-50. [PMID: 28483249 PMCID: PMC5439527 DOI: 10.1016/j.ijporl.2017.03.025] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Revised: 03/16/2017] [Accepted: 03/18/2017] [Indexed: 11/29/2022]
Abstract
OBJECTIVE Hearing loss rates in infants admitted to neonatal intensive care units (NICU) run at 2-15%, compared to 0.3% in full-term births. The etiology of this difference remains poorly understood. We examined whether the level of ambient sound and/or cumulative gentamicin (an aminoglycoside) exposure affect NICU hearing screening results, as either exposure can cause acquired, permanent hearing loss. We hypothesized that higher levels of ambient sound in the NICU, and/or gentamicin dosing, increase the risk of referral on the distortion product otoacoustic emission (DPOAE) assessments and/or automated auditory brainstem response (AABR) screens. METHODS This was a prospective pilot outcomes study of 82 infants (<37 weeks gestational age) admitted to the NICU at Oregon Health & Science University. An ER-200D sound pressure level dosimeter was used to collect daily sound exposure in the NICU for each neonate. Gentamicin dosing was also calculated for each infant, including the total daily dose based on body mass (mg/kg/day), as well as the total number of treatment days. DPOAE and AABR assessments were conducted prior to discharge to evaluate hearing status. Exclusion criteria included congenital infections associated with hearing loss, and congenital craniofacial or otologic abnormalities. RESULTS The mean level of ambient sound was 62.9 dBA (range 51.8-70.6 dBA), greatly exceeding American Academy of Pediatrics (AAP) recommendation of <45.0 dBA. More than 80% of subjects received gentamicin treatment. The referral rate for (i) AABRs, (frequency range: ∼1000-4000 Hz), was 5%; (ii) DPOAEs with a broad F2 frequency range (2063-10031 Hz) was 39%; (iii) DPOAEs with a low-frequency F2 range (<4172 Hz) was 29%, and (iv) DPOAEs with a high-frequency F2 range (>4172 Hz) was 44%. DPOAE referrals were significantly greater for infants receiving >2 days of gentamicin dosing compared to fewer doses (p = 0.004). The effect of sound exposure and gentamicin treatment on hearing could not be determined due to the low number of NICU infants without gentamicin exposure (for control comparisons). CONCLUSION All infants were exposed to higher levels of ambient sound that substantially exceed AAP guidelines. More referrals were generated by DPOAE assessments than with AABR screens, with significantly more DPOAE referrals with a high-frequency F2 range, consistent with sound- and/or gentamicin-induced cochlear dysfunction. Adding higher frequency DPOAE assessments to existing NICU hearing screening protocols could better identify infants at-risk for ototoxicity.
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Affiliation(s)
- Angela C. Garinis
- Department of Otolaryngology, Oregon Health & Science University, Portland, Oregon
| | - Selena Liao
- Department of Otolaryngology, Oregon Health & Science University, Portland, Oregon
| | - Campbell P. Cross
- School of Medicine, Oregon Health & Science University, Portland, Oregon,Oregon Hearing Research Center, Oregon Health & Science University, Portland, Oregon
| | - Johnathan Galati
- Oregon Hearing Research Center, Oregon Health & Science University, Portland, Oregon
| | - Jessica L. Middaugh
- Department of Otolaryngology, Oregon Health & Science University, Portland, Oregon
| | - Jess C. Mace
- Department of Otolaryngology, Oregon Health & Science University, Portland, Oregon
| | - Anna-Marie Wood
- Oregon Hearing Research Center, Oregon Health & Science University, Portland, Oregon
| | - Lindsey McEvoy
- Oregon Hearing Research Center, Oregon Health & Science University, Portland, Oregon
| | - Lauren Moneta
- Department of Otolaryngology, Oregon Health & Science University, Portland, Oregon
| | - Troy Lubianski
- Oregon Clinical and Translational Research Institute, Oregon Health & Science University, Portland, Oregon
| | - Noe Coopersmith
- Oregon Clinical and Translational Research Institute, Oregon Health & Science University, Portland, Oregon
| | - Nicholas Vigo
- School of Medicine, Oregon Health & Science University, Portland, Oregon
| | - Christopher Hart
- School of Medicine, Oregon Health & Science University, Portland, Oregon
| | - Artur Riddle
- School of Medicine, Oregon Health & Science University, Portland, Oregon
| | - Olivia Ettinger
- Oregon Hearing Research Center, Oregon Health & Science University, Portland, Oregon
| | - Casey Nold
- Oregon Clinical and Translational Research Institute, Oregon Health & Science University, Portland, Oregon
| | - Heather Durham
- Child Development and Research Center, Oregon Health & Science University, Portland, Oregon
| | - Carol MacArthur
- Department of Otolaryngology, Oregon Health & Science University, Portland, Oregon
| | - Cynthia McEvoy
- Department of Neonatology, Oregon Health & Science University, Portland, Oregon
| | - Peter S. Steyger
- Department of Otolaryngology, Oregon Health & Science University, Portland, Oregon,Oregon Hearing Research Center, Oregon Health & Science University, Portland, Oregon
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8
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O’Sullivan ME, Perez A, Lin R, Sajjadi A, Ricci AJ, Cheng AG. Towards the Prevention of Aminoglycoside-Related Hearing Loss. Front Cell Neurosci 2017; 11:325. [PMID: 29093664 PMCID: PMC5651232 DOI: 10.3389/fncel.2017.00325] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 09/30/2017] [Indexed: 01/08/2023] Open
Abstract
Aminoglycosides are potent antibiotics deployed worldwide despite their known side-effect of sensorineural hearing loss. The main etiology of this sensory deficit is death of inner ear sensory hair cells selectively triggered by aminoglycosides. For decades, research has sought to unravel the molecular events mediating sensory cell demise, emphasizing the roles of reactive oxygen species and their potentials as therapeutic targets. Studies in recent years have revealed candidate transport pathways including the mechanotransducer channel for drug entry into sensory cells. Once inside sensory cells, intracellular targets of aminoglycosides, such as the mitochondrial ribosomes, are beginning to be elucidated. Based on these results, less ototoxic aminoglycoside analogs are being generated and may serve as alternate antimicrobial agents. In this article, we review the latest findings on mechanisms of aminoglycoside entry into hair cells, their intracellular actions and potential therapeutic targets for preventing aminoglycoside ototoxicity.
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Affiliation(s)
- Mary E. O’Sullivan
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA, United States
| | - Adela Perez
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA, United States
| | - Randy Lin
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA, United States
| | - Autefeh Sajjadi
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA, United States
| | - Anthony J. Ricci
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA, United States
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, United States
- *Correspondence: Anthony J. Ricci Alan G. Cheng
| | - Alan G. Cheng
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA, United States
- *Correspondence: Anthony J. Ricci Alan G. Cheng
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Bartos A, Grondin Y, Bortoni ME, Ghelfi E, Sepulveda R, Carroll J, Rogers RA. Pre-conditioning with near infrared photobiomodulation reduces inflammatory cytokines and markers of oxidative stress in cochlear hair cells. JOURNAL OF BIOPHOTONICS 2016; 9:1125-1135. [PMID: 26790619 DOI: 10.1002/jbio.201500209] [Citation(s) in RCA: 263] [Impact Index Per Article: 32.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 12/11/2015] [Accepted: 12/12/2015] [Indexed: 06/05/2023]
Abstract
Hearing loss is a serious occupational health problem worldwide. Noise, aminoglycoside antibiotics and chemotherapeutic drugs induce hearing loss through changes in metabolic functions resulting in sensory cell death in the cochlea. Metabolic sequelae from noise exposure increase production of nitric oxide (NO) and Reactive Oxygen Species (ROS) contributing to higher levels of oxidative stress beyond the physiologic threshold levels of intracellular repair. Photobiomodulation (PBM) therapy is a light treatment involving endogenous chromophores commonly used to reduce inflammation and promote tissue repair. Near infrared light (NIR) from Light Emitting Diodes (LED) at 810 nm wavelength were used as a biochemical modulator of cytokine response in cultured HEI-OC1 auditory cells placed under oxidative stress. Results reported here show that NIR PBM at 810 nm, 30 mW/cm2 , 100 seconds, 1.0 J, 3 J/cm2 altered mitochondrial metabolism and oxidative stress response for up to 24 hours post treatment. We report a decrease of inflammatory cytokines and stress levels resulting from NIR applied to HEI-OC1 auditory cells before treatment with gentamicin or lipopolysaccharide. These results show that cells pretreated with NIR exhibit reduction of proinflammatory markers that correlate with inhibition of mitochondrial superoxide, ROS and NO in response to continuous oxidative stress challenges. Non-invasive biomolecular down regulation of proinflammatory intracellular metabolic pathways and suppression of oxidative stress via NIR may have the potential to develop novel therapeutic approaches to address noise exposure and ototoxic compounds associated with hearing loss.
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Affiliation(s)
- Adam Bartos
- Harvard University - Harvard T.H. Chan School of Public Health, Molecular and Integrative Physiological Sciences - Department of Environmental Health, Building 1, 665 Huntington Ave, Boston, MA, 02115, USA
| | - Yohann Grondin
- Harvard University - Harvard T.H. Chan School of Public Health, Molecular and Integrative Physiological Sciences - Department of Environmental Health, Building 1, 665 Huntington Ave, Boston, MA, 02115, USA
| | - Magda E Bortoni
- Harvard University - Harvard T.H. Chan School of Public Health, Molecular and Integrative Physiological Sciences - Department of Environmental Health, Building 1, 665 Huntington Ave, Boston, MA, 02115, USA
| | - Elisa Ghelfi
- Harvard University - Harvard T.H. Chan School of Public Health, Molecular and Integrative Physiological Sciences - Department of Environmental Health, Building 1, 665 Huntington Ave, Boston, MA, 02115, USA
| | - Rosalinda Sepulveda
- Harvard University - Harvard T.H. Chan School of Public Health, Molecular and Integrative Physiological Sciences - Department of Environmental Health, Building 1, 665 Huntington Ave, Boston, MA, 02115, USA
| | - James Carroll
- THOR Photomedicine Ltd, Chesham, HP5 1LF, United Kingdom
| | - Rick A Rogers
- Harvard University - Harvard T.H. Chan School of Public Health, Molecular and Integrative Physiological Sciences - Department of Environmental Health, Building 1, 665 Huntington Ave, Boston, MA, 02115, USA
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10
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Koo JW, Quintanilla-Dieck L, Jiang M, Liu J, Urdang ZD, Allensworth JJ, Cross CP, Li H, Steyger PS. Endotoxemia-mediated inflammation potentiates aminoglycoside-induced ototoxicity. Sci Transl Med 2016. [PMID: 26223301 DOI: 10.1126/scitranslmed.aac5546] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The ototoxic aminoglycoside antibiotics are essential to treat severe bacterial infections, particularly in neonatal intensive care units. Using a bacterial lipopolysaccharide (LPS) experimental model of sepsis, we tested whether LPS-mediated inflammation potentiates cochlear uptake of aminoglycosides and permanent hearing loss in mice. Using confocal microscopy and enzyme-linked immunosorbent assays, we found that low-dose LPS (endotoxemia) greatly increased cochlear concentrations of aminoglycosides and resulted in vasodilation of cochlear capillaries without inducing paracellular flux across the blood-labyrinth barrier (BLB) or elevating serum concentrations of the drug. Additionally, endotoxemia increased expression of both serum and cochlear inflammatory markers. These LPS-induced changes, classically mediated by Toll-like receptor 4 (TLR4), were attenuated in TLR4-hyporesponsive mice. Multiday dosing with aminoglycosides during chronic endotoxemia induced greater hearing threshold shifts and sensory cell loss compared to mice without endotoxemia. Thus, endotoxemia-mediated inflammation enhanced aminoglycoside trafficking across the BLB and potentiated aminoglycoside-induced ototoxicity. These data indicate that patients with severe infections are at greater risk of aminoglycoside-induced hearing loss than previously recognized.
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Affiliation(s)
- Ja-Won Koo
- Oregon Hearing Research Center, Department of Otolaryngology, Oregon Health & Science University, 3181 Southwest Sam Jackson Park Road, Portland, OR 97239, USA. Department of Otorhinolaryngology, Seoul National University College of Medicine, Seoul National University Bundang Hospital, 173-82 Kumiro, Bundang-gu, Seongnam 463-707, Republic of Korea
| | - Lourdes Quintanilla-Dieck
- Oregon Hearing Research Center, Department of Otolaryngology, Oregon Health & Science University, 3181 Southwest Sam Jackson Park Road, Portland, OR 97239, USA
| | - Meiyan Jiang
- Oregon Hearing Research Center, Department of Otolaryngology, Oregon Health & Science University, 3181 Southwest Sam Jackson Park Road, Portland, OR 97239, USA
| | - Jianping Liu
- Oregon Hearing Research Center, Department of Otolaryngology, Oregon Health & Science University, 3181 Southwest Sam Jackson Park Road, Portland, OR 97239, USA. Department of Otology and Skull Base Surgery, Eye Ear Nose and Throat Hospital, Fudan University, Shanghai 200031, China
| | - Zachary D Urdang
- Oregon Hearing Research Center, Department of Otolaryngology, Oregon Health & Science University, 3181 Southwest Sam Jackson Park Road, Portland, OR 97239, USA
| | - Jordan J Allensworth
- Oregon Hearing Research Center, Department of Otolaryngology, Oregon Health & Science University, 3181 Southwest Sam Jackson Park Road, Portland, OR 97239, USA
| | - Campbell P Cross
- Oregon Hearing Research Center, Department of Otolaryngology, Oregon Health & Science University, 3181 Southwest Sam Jackson Park Road, Portland, OR 97239, USA
| | - Hongzhe Li
- Oregon Hearing Research Center, Department of Otolaryngology, Oregon Health & Science University, 3181 Southwest Sam Jackson Park Road, Portland, OR 97239, USA
| | - Peter S Steyger
- Oregon Hearing Research Center, Department of Otolaryngology, Oregon Health & Science University, 3181 Southwest Sam Jackson Park Road, Portland, OR 97239, USA.
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11
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Loughman K, Hall J, Knowlton S, Sindeldecker D, Gilson T, Schmitt DM, Birch JWM, Gajtka T, Kobe BN, Florjanczyk A, Ingram J, Bakshi CS, Horzempa J. Temperature-Dependent Gentamicin Resistance of Francisella tularensis is Mediated by Uptake Modulation. Front Microbiol 2016; 7:37. [PMID: 26858709 PMCID: PMC4729955 DOI: 10.3389/fmicb.2016.00037] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Accepted: 01/11/2016] [Indexed: 11/13/2022] Open
Abstract
Gentamicin (Gm) is an aminoglycoside commonly used to treat bacterial infections such as tularemia – the disease caused by Francisella tularensis. In addition to being pathogenic, F. tularensis is found in environmental niches such as soil where this bacterium likely encounters Gm producers (Micromonospora sp.). Here we show that F. tularensis exhibits increased resistance to Gm at ambient temperature (26°C) compared to mammalian body temperature (37°C). To evaluate whether F. tularensis was less permeable to Gm at 26°C, a fluorescent marker [Texas Red (Tr)] was conjugated with Gm, yielding Tr-Gm. Bacteria incubated at 26°C showed reduced fluorescence compared to those at 37°C when exposed to Tr-Gm suggesting that uptake of Gm was reduced at 26°C. Unconjugated Gm competitively inhibited uptake of Tr-Gm, demonstrating that this fluorescent compound was taken up similarly to unconjugated Gm. Lysates of F. tularensis bacteria incubated with Gm at 37°C inhibited the growth of Escherichia coli significantly more than lysates from bacteria incubated at 26°C, further indicating reduced uptake at this lower temperature. Other facultative pathogens (Listeria monocytogenes and Klebsiella pneumoniae) exhibited increased resistance to Gm at 26°C suggesting that the results generated using F. tularensis may be generalizable to diverse bacteria. Regulation of the uptake of antibiotics provides a mechanism by which facultative pathogens survive alongside antibiotic-producing microbes in nature.
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Affiliation(s)
- Kathleen Loughman
- Department of Natural Sciences and Mathematics, West Liberty University West Liberty, WV, USA
| | - Jesse Hall
- Department of Natural Sciences and Mathematics, West Liberty University West Liberty, WV, USA
| | - Samantha Knowlton
- Department of Natural Sciences and Mathematics, West Liberty University West Liberty, WV, USA
| | - Devin Sindeldecker
- Department of Natural Sciences and Mathematics, West Liberty University West Liberty, WV, USA
| | - Tricia Gilson
- Department of Natural Sciences and Mathematics, West Liberty University West Liberty, WV, USA
| | - Deanna M Schmitt
- Department of Natural Sciences and Mathematics, West Liberty University West Liberty, WV, USA
| | - James W-M Birch
- Department of Natural Sciences and Mathematics, West Liberty University West Liberty, WV, USA
| | - Tara Gajtka
- Department of Natural Sciences and Mathematics, West Liberty University West Liberty, WV, USA
| | - Brianna N Kobe
- Department of Natural Sciences and Mathematics, West Liberty University West Liberty, WV, USA
| | - Aleksandr Florjanczyk
- Department of Natural Sciences and Mathematics, West Liberty University West Liberty, WV, USA
| | - Jenna Ingram
- Department of Natural Sciences and Mathematics, West Liberty University West Liberty, WV, USA
| | - Chandra S Bakshi
- Department of Microbiology and Immunology, New York Medical College Valhalla, NY, USA
| | - Joseph Horzempa
- Department of Natural Sciences and Mathematics, West Liberty University West Liberty, WV, USA
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12
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Cross CP, Liao S, Urdang ZD, Srikanth P, Garinis AC, Steyger PS. Effect of sepsis and systemic inflammatory response syndrome on neonatal hearing screening outcomes following gentamicin exposure. Int J Pediatr Otorhinolaryngol 2015; 79:1915-9. [PMID: 26384832 PMCID: PMC4593761 DOI: 10.1016/j.ijporl.2015.09.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Revised: 09/01/2015] [Accepted: 09/01/2015] [Indexed: 12/30/2022]
Abstract
OBJECTIVES Hearing loss in neonatal intensive care unit (NICU) graduates range from 2% to 15% compared to 0.3% in full-term births, and the etiology of this discrepancy remains unknown. The majority of NICU admissions receive potentially ototoxic aminoglycoside therapy, such as gentamicin, for presumed sepsis. Endotoxemia and inflammation are associated with increased cochlear uptake of aminoglycosides and potentiated ototoxicity in mice. We tested the hypothesis that sepsis or systemic inflammatory response syndrome (SIRS) and intravenous gentamicin exposure increases the risk of hearing loss in NICU admissions. METHODS The Institutional Review Board at Oregon Health & Science University (OHSU) approved this study design. Two hundred and eight infants met initial criteria, and written, informed consent were obtained from parents or guardians of 103 subjects ultimately enrolled in this study. Prospective data from 91 of the enrolled subjects at OHSU Doernbecher Children's Hospital Neonatal Care Center were processed. Distortion product otoacoustic emissions (DPOAEs; f2 frequency range: 2063-10,031 Hz) were obtained prior to discharge to assess auditory performance. To pass the DPOAE screen, normal responses in >6 of 10 frequencies in both ears were required; otherwise the subject was considered a "referral" for a diagnostic hearing evaluation after discharge. Cumulative dosing data and diagnosis of neonatal sepsis or SIRS were obtained from OHSU's electronic health record system, and the data processed to obtain risk ratios. RESULTS Using these DPOAE screening criteria, 36 (39.5%) subjects would be referred. Seventy-four (81%) subjects had intravenous gentamicin exposure. Twenty (22%) had ≥4 days of gentamicin, and 71 (78%) had <4 days. The risk ratio (RR) of referral with ≥4 days of gentamicin was 1.92 (p=0.01). Eighteen subjects had sepsis or met neonatal SIRS criteria, 9 of whom had ≥5 days of gentamicin and a DPOAE referral risk ratio of 2.12 (p=0.02) compared to all other subjects. Combining subjects with either vancomycin or furosemide overlap with gentamicin treatment yielded an almost significant risk ratio (RR=1.77, p=0.05) compared to the rest of the cohort. CONCLUSIONS We report an increased risk of referral with DPOAE screening for those receiving ≥4 days of intravenous gentamicin administration that may contribute to the greater prevalence of hearing loss in NICU graduates. We propose an expanded prospective study to gather a larger cohort of subjects, identifying those with sepsis or neonatal SIRS, to increase the statistical power of this study design. Subsequent studies also need to obtain follow-up diagnostic audiological data to verify whether the outcomes of DPOAE screening, in addition to the standard AABR screen, is a reliable predictor of permanent hearing loss following gentamicin exposure in the NICU.
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Affiliation(s)
- Campbell P Cross
- Oregon Hearing Research Center, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA.
| | - Selena Liao
- Otolaryngology, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA
| | - Zachary D Urdang
- Oregon Hearing Research Center, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA; Oregon Health & Science University, MD/PhD Program, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA
| | - Priya Srikanth
- Department of Public Health & Preventive Medicine, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Mail Code CB 669, Portland, OR 97239, USA
| | - Angela C Garinis
- Oregon Hearing Research Center, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA; Portland Veterans Administration, National Center for Rehabilitative Auditory Research (NCRAR), 3710 SW US Veterans Hospital Road, Portland, OR 97239, USA
| | - Peter S Steyger
- Oregon Hearing Research Center, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA; Otolaryngology, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA; Portland Veterans Administration, National Center for Rehabilitative Auditory Research (NCRAR), 3710 SW US Veterans Hospital Road, Portland, OR 97239, USA.
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Abstract
Hearing loss is the most common congenital sensory impairment. According to National Health and Nutrition Examination Survey data from 2001 to 2008, 20.3% of subjects aged greater than or equal to 12 had unilateral or bilateral hearing loss. The World Health Organization notes that, worldwide, there are 360 million people with disabling hearing loss, with 50% preventable. Although many hearing losses are acquired, many others are manifestations of preexisting conditions. The purpose of a pediatric hearing evaluation is to identify the degree and type of hearing loss and etiology and to outline a comprehensive strategy that supports language and social development and communication.
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Affiliation(s)
- Margaret A Kenna
- Otolaryngology and Communication Enhancement, Boston Children's Hospital, Harvard Medical School, 300 Longwood Avenue, BCH3129, Boston, MA 02115, USA.
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14
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Reiss LAJ, Stark G, Nguyen-Huynh AT, Spear KA, Zhang H, Tanaka C, Li H. Morphological correlates of hearing loss after cochlear implantation and electro-acoustic stimulation in a hearing-impaired Guinea pig model. Hear Res 2015; 327:163-74. [PMID: 26087114 DOI: 10.1016/j.heares.2015.06.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Revised: 04/30/2015] [Accepted: 06/03/2015] [Indexed: 01/25/2023]
Abstract
Hybrid or electro-acoustic stimulation (EAS) cochlear implants (CIs) are designed to provide high-frequency electric hearing together with residual low-frequency acoustic hearing. However, 30-50% of EAS CI recipients lose residual hearing after implantation. The objective of this study was to determine the mechanisms of EAS-induced hearing loss in an animal model with high-frequency hearing loss. Guinea pigs were exposed to 24 h of noise (12-24 kHz at 116 dB) to induce a high-frequency hearing loss. After recovery, two groups of animals were implanted (n = 6 per group), with one group receiving chronic acoustic and electric stimulation for 10 weeks, and the other group receiving no stimulation during this time frame. A third group (n = 6) was not implanted, but received chronic acoustic stimulation. Auditory brainstem responses were recorded biweekly to monitor changes in hearing. The organ of Corti was immunolabeled with phalloidin, anti-CtBP2, and anti-GluR2 to quantify hair cells, ribbons and post-synaptic receptors. The lateral wall was immunolabeled with phalloidin and lectin to quantify stria vascularis capillary diameters. Bimodal or trimodal diameter distributions were observed; the number and location of peaks were objectively determined using the Aikake Information Criterion and Expectation Maximization algorithm. Noise exposure led to immediate hearing loss at 16-32 kHz for all groups. Cochlear implantation led to additional hearing loss at 4-8 kHz; this hearing loss was negatively and positively correlated with minimum and maximum peaks of the bimodal or trimodal distributions of stria vascularis capillary diameters, respectively. After chronic stimulation, no significant group changes in thresholds were seen; however, elevated thresholds at 1 kHz in implanted, stimulated animals were significantly correlated with decreased presynaptic ribbon and postsynaptic receptor counts. Inner and outer hair cell counts did not differ between groups and were not correlated with threshold shifts at any frequency. As in the previous study in a normal-hearing model, stria vascularis capillary changes were associated with immediate hearing loss after implantation, while little to no hair cell loss was observed even in cochlear regions with threshold shifts as large as 40-50 dB. These findings again support a role of lateral wall blood flow changes, rather than hair cell loss, in hearing loss after surgical trauma, and implicate the endocochlear potential as a factor in implantation-induced hearing loss. Further, the analysis of the hair cell ribbons and post-synaptic receptors suggest that delayed hearing loss may be linked to synapse or peripheral nerve loss due to stimulation excitotoxicity or inflammation. Further research is needed to separate these potential mechanisms of delayed hearing loss.
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Affiliation(s)
- Lina A J Reiss
- Oregon Hearing Research Center, Department of Otolaryngology, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA.
| | - Gemaine Stark
- Oregon Hearing Research Center, Department of Otolaryngology, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA
| | - Anh T Nguyen-Huynh
- Oregon Hearing Research Center, Department of Otolaryngology, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA
| | - Kayce A Spear
- Oregon Hearing Research Center, Department of Otolaryngology, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA
| | - Hongzheng Zhang
- Oregon Hearing Research Center, Department of Otolaryngology, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA; Department of Otolaryngology Head & Neck Surgery, Zhujiang Hospital of Southern Medical University, Guangzhou 510280, China
| | - Chiemi Tanaka
- Oregon Hearing Research Center, Department of Otolaryngology, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA; Department of Communication Sciences and Disorders, John A. Burns School of Medicine, University of Hawai'i at Mānoa, 677 Ala Moana Blvd, Honolulu, HI 96816, USA
| | - Hongzhe Li
- Oregon Hearing Research Center, Department of Otolaryngology, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA
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15
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Li H, Kachelmeier A, Furness DN, Steyger PS. Local mechanisms for loud sound-enhanced aminoglycoside entry into outer hair cells. Front Cell Neurosci 2015; 9:130. [PMID: 25926770 PMCID: PMC4396448 DOI: 10.3389/fncel.2015.00130] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Accepted: 03/20/2015] [Indexed: 12/03/2022] Open
Abstract
Loud sound exposure exacerbates aminoglycoside ototoxicity, increasing the risk of permanent hearing loss and degrading the quality of life in affected individuals. We previously reported that loud sound exposure induces temporary threshold shifts (TTS) and enhances uptake of aminoglycosides, like gentamicin, by cochlear outer hair cells (OHCs). Here, we explore mechanisms by which loud sound exposure and TTS could increase aminoglycoside uptake by OHCs that may underlie this form of ototoxic synergy. Mice were exposed to loud sound levels to induce TTS, and received fluorescently-tagged gentamicin (GTTR) for 30 min prior to fixation. The degree of TTS was assessed by comparing auditory brainstem responses (ABRs) before and after loud sound exposure. The number of tip links, which gate the GTTR-permeant mechanoelectrical transducer (MET) channels, was determined in OHC bundles, with or without exposure to loud sound, using scanning electron microscopy. We found wide-band noise (WBN) levels that induce TTS also enhance OHC uptake of GTTR compared to OHCs in control cochleae. In cochlear regions with TTS, the increase in OHC uptake of GTTR was significantly greater than in adjacent pillar cells. In control mice, we identified stereociliary tip links at ~50% of potential positions in OHC bundles. However, the number of OHC tip links was significantly reduced in mice that received WBN at levels capable of inducing TTS. These data suggest that GTTR uptake by OHCs during TTS occurs by increased permeation of surviving, mechanically-gated MET channels, and/or non-MET aminoglycoside-permeant channels activated following loud sound exposure. Loss of tip links would hyperpolarize hair cells and potentially increase drug uptake via aminoglycoside-permeant channels expressed by hair cells. The effect of TTS on aminoglycoside-permeant channel kinetics will shed new light on the mechanisms of loud sound-enhanced aminoglycoside uptake, and consequently on ototoxic synergy.
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Affiliation(s)
- Hongzhe Li
- Oregon Hearing Research Center, Oregon Health & Science University Portland, OR, USA
| | - Allan Kachelmeier
- Oregon Hearing Research Center, Oregon Health & Science University Portland, OR, USA
| | | | - Peter S Steyger
- Oregon Hearing Research Center, Oregon Health & Science University Portland, OR, USA
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16
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Uptake of fluorescent gentamicin by peripheral vestibular cells after systemic administration. PLoS One 2015; 10:e0120612. [PMID: 25793391 PMCID: PMC4368668 DOI: 10.1371/journal.pone.0120612] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Accepted: 02/04/2015] [Indexed: 11/28/2022] Open
Abstract
Objective In addition to cochleotoxicity, systemic aminoglycoside pharmacotherapy causes vestibulotoxicity resulting in imbalance and visual dysfunction. The underlying trafficking routes of systemically-administered aminoglycosides from the vasculature to the vestibular sensory hair cells are largely unknown. We investigated the trafficking of systemically-administered gentamicin into the peripheral vestibular system in C56Bl/6 mice using fluorescence-tagged gentamicin (gentamicin-Texas-Red, GTTR) imaged by scanning laser confocal microscopy to determine the cellular distribution and intensity of GTTR fluorescence in the three semicircular canal cristae, utricular, and saccular maculae at 5 time points over 4 hours. Results Low intensity GTTR fluorescence was detected at 0.5 hours as both discrete puncta and diffuse cytoplasmic fluorescence. The intensity of cytoplasmic fluorescence peaked at 3 hours, while punctate fluorescence was plateaued after 3 hours. At 0.5 and 1 hour, higher levels of diffuse GTTR fluorescence were present in transitional cells compared to hair cells and supporting cells. Sensory hair cells typically exhibited only diffuse cytoplasmic fluorescence at all time-points up to 4 hours in this study. In contrast, non-sensory cells rapidly exhibited both intense fluorescent puncta and weaker, diffuse fluorescence throughout the cytosol. The numbers and size of fluorescent puncta in dark cells and transitional cells increased over time. There is no preferential GTTR uptake by the five peripheral vestibular organs’ sensory cells. Control vestibular tissues exposed to Dulbecco’s phosphate-buffered saline or hydrolyzed Texas Red had negligible fluorescence. Conclusions All peripheral vestibular cells rapidly take up systemically-administered GTTR, reaching peak intensity 3 hours after injection. Sensory hair cells exhibited only diffuse fluorescence, while non-sensory cells displayed both diffuse and punctate fluorescence. Transitional cells may act as a primary pathway for trafficking of systemic GTTR from the vasculature to endolymph prior to entering hair cells.
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17
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Sodium-glucose transporter-2 (SGLT2; SLC5A2) enhances cellular uptake of aminoglycosides. PLoS One 2014; 9:e108941. [PMID: 25268124 PMCID: PMC4182564 DOI: 10.1371/journal.pone.0108941] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Accepted: 08/26/2014] [Indexed: 12/20/2022] Open
Abstract
Aminoglycoside antibiotics, like gentamicin, continue to be clinically essential worldwide to treat life-threatening bacterial infections. Yet, the ototoxic and nephrotoxic side-effects of these drugs remain serious complications. A major site of gentamicin uptake and toxicity resides within kidney proximal tubules that also heavily express electrogenic sodium-glucose transporter-2 (SGLT2; SLC5A2) in vivo. We hypothesized that SGLT2 traffics gentamicin, and promotes cellular toxicity. We confirmed in vitro expression of SGLT2 in proximal tubule-derived KPT2 cells, and absence in distal tubule-derived KDT3 cells. D-glucose competitively decreased the uptake of 2-(N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)-2-deoxyglucose (2-NBDG), a fluorescent analog of glucose, and fluorescently-tagged gentamicin (GTTR) by KPT2 cells. Phlorizin, an SGLT2 antagonist, strongly inhibited uptake of 2-NBDG and GTTR by KPT2 cells in a dose- and time-dependent manner. GTTR uptake was elevated in KDT3 cells transfected with SGLT2 (compared to controls); and this enhanced uptake was attenuated by phlorizin. Knock-down of SGLT2 expression by siRNA reduced gentamicin-induced cytotoxicity. In vivo, SGLT2 was robustly expressed in kidney proximal tubule cells of heterozygous, but not null, mice. Phlorizin decreased GTTR uptake by kidney proximal tubule cells in Sglt2+/− mice, but not in Sglt2−/− mice. However, serum GTTR levels were elevated in Sglt2−/− mice compared to Sglt2+/− mice, and in phlorizin-treated Sglt2+/− mice compared to vehicle-treated Sglt2+/− mice. Loss of SGLT2 function by antagonism or by gene deletion did not affect gentamicin cochlear loading or auditory function. Phlorizin did not protect wild-type mice from kanamycin-induced ototoxicity. We conclude that SGLT2 can traffic gentamicin and contribute to gentamicin-induced cytotoxicity.
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Kent A, Turner MA, Sharland M, Heath PT. Aminoglycoside toxicity in neonates: something to worry about? Expert Rev Anti Infect Ther 2014; 12:319-31. [PMID: 24455994 DOI: 10.1586/14787210.2014.878648] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Toxicity has limited the use of aminoglycosides and adult studies report high rates of both ototoxicity and nephrotoxicity. Conversely paediatric studies have shown lower rates and extended interval dosing may have reduced toxicity further. We review the animal and human evidence for aminoglycoside toxicity in neonates including mechanisms, measurement and rates of toxicity; and differences between aminoglycosides and dosing regimens. We discuss genetic susceptibility and the impact of other synergistic effects.
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Affiliation(s)
- Alison Kent
- Paediatric Infectious Diseases Research Group, Division of Clinical Sciences, St. George's, University of London, London, UK
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Wang T, Yang YQ, Karasawa T, Wang Q, Phillips A, Guan BC, Ma KT, Jiang M, Xie DH, Steyger PS, Jiang ZG. Bumetanide hyperpolarizes madin-darby canine kidney cells and enhances cellular gentamicin uptake by elevating cytosolic Ca(2+) thus facilitating intermediate conductance Ca(2+)--activated potassium channels. Cell Biochem Biophys 2013; 65:381-98. [PMID: 23109177 DOI: 10.1007/s12013-012-9442-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Loop diuretics such as bumetanide and furosemide enhance aminoglycoside ototoxicity when co-administered to patients and animal models. The underlying mechanism(s) is poorly understood. We investigated the effect of these diuretics on cellular uptake of aminoglycosides, using Texas Red-tagged gentamicin (GTTR), and intracellular/whole-cell recordings of Madin-Darby canine kidney (MDCK) cells. We found that bumetanide and furosemide dose-dependently enhanced cytoplasmic GTTR fluorescence by ~60 %. This enhancement was suppressed by La(3+), a non-selective cation channel (NSCC) blocker, and by K(+) channel blockers Ba(2+) and clotrimazole, but not by tetraethylammonium (TEA), 4-aminopyridine (4-AP) or glipizide, nor by Cl(-) channel blockers diphenylamine-2-carboxylic acid (DPC), niflumic acid (NFA), and CFTRinh-172. Bumetanide and furosemide hyperpolarized MDCK cells by ~14 mV, increased whole-cell I/V slope conductance; the bumetanide-induced net current I/V showed a reversal potential (V r) ~-80 mV. Bumetanide-induced hyperpolarization and I/V change was suppressed by Ba(2+) or clotrimazole, and absent in elevated [Ca(2+)]i, but was not affected by apamin, 4-AP, TEA, glipizide, DPC, NFA, or CFTRinh-172. Bumetanide and furosemide stimulated a surge of Fluo-4-indicated cytosolic Ca(2+). Ba(2+) and clotrimazole alone depolarized cells by ~18 mV and reduced I/V slope with a net current V r near -85 mV, and reduced GTTR uptake by ~20 %. La(3+) alone hyperpolarized the cells by ~-14 mV, reduced the I/V slope with a net current V r near -10 mV, and inhibited GTTR uptake by ~50 %. In the presence of La(3+), bumetanide-caused negligible change in potential or I/V. We conclude that NSCCs constitute a major cell entry pathway for cationic aminoglycosides; bumetanide enhances aminoglycoside uptake by hyperpolarizing cells that increases the cation influx driving force; and bumetanide-induced hyperpolarization is caused by elevating intracellular Ca(2+) and thus facilitating activation of the intermediate conductance Ca(2+)-activated K(+) channels.
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Affiliation(s)
- Tian Wang
- Oregon Hearing Research Center, NRC04, Department of Otolaryngology, Oregon Health & Science University, Portland, OR 97239, USA
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20
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Zhai F, Zhang R, Zhang T, Steyger PS, Dai CF. Preclinical and clinical studies of unrelieved aural fullness following intratympanic gentamicin injection in patients with intractable Ménière's disease. Audiol Neurootol 2013; 18:297-306. [PMID: 24008307 DOI: 10.1159/000351805] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2012] [Accepted: 04/30/2013] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVE To clarify whether gentamicin affects vestibular dark cells in guinea pigs and relieves patients of aural fullness with intractable Ménière's disease following intratympanic administration. MATERIALS AND METHODS Purified gentamicin-Texas Red (GTTR) was injected intratympanically in guinea pigs that were sacrificed at 1, 3, 7, 14 and 28 days. GTTR uptake was examined in hair cells, and transitional cells and dark cells in vestibular end-organs were examined. Specific attention was paid to its distribution in dark cells under confocal microscopy, and the ultrastructure of dark cells using electron microscopy, following intratympanic injection. RESULTS Dark cells in the semicircular canals showed weak GTTR uptake at 1, 3, 7, 14 and 28 days after intratympanic injection, with no significant differences at various time points after injection. However, the adjacent transitional cells demonstrated intense GTTR uptake that was retained for at least 28 days. Ultrastructural studies demonstrated negligible characteristics associated with apoptosis or necrosis in these dark cells. The tight junctions between dark cells showed no signs of disruption at 7 or 28 days after injection. CONCLUSION Intratympanic gentamicin has little direct impact on vestibular dark cells. CLINICAL APPLICATION A modified low-dose titration intratympanic approach was used in 29 patients with intractable vertigo and the clinical outcomes were followed. Aural fullness following intratympanic gentamicin injection was not relieved based on our subjective scales, demonstrated by no statistically significant difference between preinjection (4.16 ± 3.08) and postinjection (3.58 ± 2.93; p > 0.05) aural fullness scores. Vertigo control was achieved in 88% of patients, with hearing deterioration identified in 16% of patients. Intratympanic gentamicin administration might not lead to relief of aural fullness in patients with intractable vertigo, although it can achieve a high vertigo control rate with some cochleotoxicity.
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Affiliation(s)
- Feng Zhai
- Department of Otology and Skull Base Surgery, Eye, Ear, Nose and Throat Hospital, Fudan University, Shanghai, China
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21
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Staecker H, Rodgers B. Developments in delivery of medications for inner ear disease. Expert Opin Drug Deliv 2013; 10:639-50. [PMID: 23560526 DOI: 10.1517/17425247.2013.766167] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
INTRODUCTION Hearing loss, tinnitus and balance disturbance represent common diseases that have tremendous impact on quality of life. Despite the high incidence of inner ear disease in the general population, there are currently no dedicated pharmacologic interventions available to treat these problems. AREAS COVERED This review will focus on how treatment of inner ear disease is moving toward local delivery at the end organ level. The authors will discuss current practice, ongoing clinical trials and potential areas of development such as hair cell regeneration and neurotrophin therapy. EXPERT OPINION The inner ear is accessible through the middle ear via the oval and round windows allowing diffusion of drugs into the perilymph. With a better understanding of the physiology of the inner ear and the underlying molecular causes of inner ear disease there is great potential for the development of novel therapeutics that can be locally administered. At present, there is a rapid development of drugs to target diverse inner ear diseases that cause sensorineural hearing loss and balance dysfunction.
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Affiliation(s)
- Hinrich Staecker
- University of Kansas School of Medicine, Department of Otolaryngology Head and Neck Surgery, MS 3010, 3901 Rainbow Blvd, Kansas City, KS 66160, USA.
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22
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Patel M, Cai Q, Ding D, Salvi R, Hu Z, Hu BH. The miR-183/Taok1 target pair is implicated in cochlear responses to acoustic trauma. PLoS One 2013; 8:e58471. [PMID: 23472202 PMCID: PMC3589350 DOI: 10.1371/journal.pone.0058471] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Accepted: 02/05/2013] [Indexed: 12/31/2022] Open
Abstract
Acoustic trauma, one of the leading causes of sensorineural hearing loss, induces sensory hair cell damage in the cochlea. Identifying the molecular mechanisms involved in regulating sensory hair cell death is critical towards developing effective treatments for preventing hair cell damage. Recently, microRNAs (miRNAs) have been shown to participate in the regulatory mechanisms of inner ear development and homeostasis. However, their involvement in cochlear sensory cell degeneration following acoustic trauma is unknown. Here, we profiled the expression pattern of miRNAs in the cochlear sensory epithelium, defined miRNA responses to acoustic overstimulation, and explored potential mRNA targets of miRNAs that may be responsible for the stress responses of the cochlea. Expression analysis of miRNAs in the cochlear sensory epithelium revealed constitutive expression of 176 miRNAs, many of which have not been previously reported in cochlear tissue. Exposure to intense noise caused significant threshold shift and apoptotic activity in the cochleae. Gene expression analysis of noise-traumatized cochleae revealed time-dependent transcriptional changes in the expression of miRNAs. Target prediction analysis revealed potential target genes of the significantly downregulated miRNAs, many of which had cell death- and apoptosis-related functions. Verification of the predicted targets revealed a significant upregulation of Taok1, a target of miRNA-183. Moreover, inhibition of miR-183 with morpholino antisense oligos in cochlear organotypic cultures revealed a negative correlation between the expression levels of miR-183 and Taok1, suggesting the presence of a miR-183/Taok1 target pair. Together, miRNA profiling as well as the target analysis and validation suggest the involvement of miRNAs in the regulation of the degenerative process of the cochlea following acoustic overstimulation. The miR-183/Taok1 target pair is likely to play a role in this regulatory process.
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Affiliation(s)
- Minal Patel
- Center for Hearing and Deafness, State University of New York at Buffalo, Buffalo, New York, United States of America
| | - Qunfeng Cai
- Center for Hearing and Deafness, State University of New York at Buffalo, Buffalo, New York, United States of America
| | - Dalian Ding
- Center for Hearing and Deafness, State University of New York at Buffalo, Buffalo, New York, United States of America
| | - Richard Salvi
- Center for Hearing and Deafness, State University of New York at Buffalo, Buffalo, New York, United States of America
| | - Zihua Hu
- Center for Computational Research, New York State Center of Excellence in Bioinformatics & Life Sciences, Department of Ophthalmology, Department of Biostatistics, Department of Medicine, State University of New York at Buffalo, Buffalo, New York, United States of America
| | - Bo Hua Hu
- Center for Hearing and Deafness, State University of New York at Buffalo, Buffalo, New York, United States of America
- * E-mail:
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23
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Uribe PM, Mueller MA, Gleichman JS, Kramer MD, Wang Q, Sibrian-Vazquez M, Strongin RM, Steyger PS, Cotanche DA, Matsui JI. Dimethyl sulfoxide (DMSO) exacerbates cisplatin-induced sensory hair cell death in zebrafish (Danio rerio). PLoS One 2013; 8:e55359. [PMID: 23383324 PMCID: PMC3562182 DOI: 10.1371/journal.pone.0055359] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Accepted: 12/28/2012] [Indexed: 12/13/2022] Open
Abstract
Inner ear sensory hair cells die following exposure to aminoglycoside antibiotics or chemotherapeutics like cisplatin, leading to permanent auditory and/or balance deficits in humans. Zebrafish (Danio rerio) are used to study drug-induced sensory hair cell death since their hair cells are similar in structure and function to those found in humans. We developed a cisplatin dose-response curve using a transgenic line of zebrafish that expresses membrane-targeted green fluorescent protein under the control of the Brn3c promoter/enhancer. Recently, several small molecule screens have been conducted using zebrafish to identify potential pharmacological agents that could be used to protect sensory hair cells in the presence of ototoxic drugs. Dimethyl sulfoxide (DMSO) is typically used as a solvent for many pharmacological agents in sensory hair cell cytotoxicity assays. Serendipitously, we found that DMSO potentiated the effects of cisplatin and killed more sensory hair cells than treatment with cisplatin alone. Yet, DMSO alone did not kill hair cells. We did not observe the synergistic effects of DMSO with the ototoxic aminoglycoside antibiotic neomycin. Cisplatin treatment with other commonly used organic solvents (i.e. ethanol, methanol, and polyethylene glycol 400) also did not result in increased cell death compared to cisplatin treatment alone. Thus, caution should be exercised when interpreting data generated from small molecule screens since many compounds are dissolved in DMSO.
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Affiliation(s)
- Phillip M. Uribe
- Department of Neuroscience, Pomona College, Claremont, California, United States of America
| | - Melissa A. Mueller
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts, United States of America
| | - Julia S. Gleichman
- Department of Neuroscience, Pomona College, Claremont, California, United States of America
| | - Matthew D. Kramer
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts, United States of America
| | - Qi Wang
- Oregon Hearing Research Center, Department of Otolaryngology, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Martha Sibrian-Vazquez
- Department of Chemistry, Portland State University, Portland, Oregon, United States of America
| | - Robert M. Strongin
- Department of Chemistry, Portland State University, Portland, Oregon, United States of America
| | - Peter S. Steyger
- Oregon Hearing Research Center, Department of Otolaryngology, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Douglas A. Cotanche
- Harvard-MIT Health Sciences and Technology, Cambridge, Massachusetts, United States of America
- Harvard Noise-Induced Hearing Loss Research Group, Harvard School of Public Health, Boston, Massachusetts, United States of America
- Department of Otolaryngology and Communication Enhancement, Boston Children’s Hospital, Boston, Massachusetts, United States of America
| | - Jonathan I. Matsui
- Department of Neuroscience, Pomona College, Claremont, California, United States of America
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts, United States of America
- Department of Otolaryngology and Communication Enhancement, Boston Children’s Hospital, Boston, Massachusetts, United States of America
- * E-mail:
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Integrity and regeneration of mechanotransduction machinery regulate aminoglycoside entry and sensory cell death. PLoS One 2013; 8:e54794. [PMID: 23359017 PMCID: PMC3554584 DOI: 10.1371/journal.pone.0054794] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Accepted: 12/14/2012] [Indexed: 12/04/2022] Open
Abstract
Sound perception requires functional hair cell mechanotransduction (MET) machinery, including the MET channels and tip-link proteins. Prior work showed that uptake of ototoxic aminoglycosides (AG) into hair cells requires functional MET channels. In this study, we examined whether tip-link proteins, including Cadherin 23 (Cdh23), regulate AG entry into hair cells. Using time-lapse microscopy on cochlear explants, we found rapid uptake of gentamicin-conjugated Texas Red (GTTR) into hair cells from three-day-old Cdh23+/+ and Cdh23v2J/+ mice, but failed to detect GTTR uptake in Cdh23v2J/v2J hair cells. Pre-treatment of wildtype cochleae with the calcium chelator 1,2-bis(o-aminophenoxy) ethane-N,N,N',N'-tetraacetic acid (BAPTA) to disrupt tip-links also effectively reduced GTTR uptake into hair cells. Both Cdh23v2J/v2J and BAPTA-treated hair cells were protected from degeneration caused by gentamicin. Six hours after BAPTA treatment, GTTR uptake remained reduced in comparison to controls; by 24 hours, drug uptake was comparable between untreated and BAPTA-treated hair cells, which again became susceptible to cell death induced by gentamicin. Together, these results provide genetic and pharmacologic evidence that tip-links are required for AG uptake and toxicity in hair cells. Because tip-links can spontaneously regenerate, their temporary breakage offers a limited time window when hair cells are protected from AG toxicity.
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25
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Abstract
Majority of hearing-loss cases with extremely preterm infants have no known etiology. There is a growing concern that the administration of aminoglycoside treatment in the noisy environment of the Neonatal Intensive Care Unit (NICU) may lead to hair-cell damage and subsequent auditory impairments. In addition, several mitochondrial DNA mutations are known to have been associated with aminoglycoside-induced hearing loss. This review provides a systematic analysis of the research in this area and elucidates the multifactorial mechanisms behind how mitochondrial DNA mutations, aminoglycosides and loud noise can potentiate ototoxicity in extremely preterm neonates. Recommended steps to minimize the risk of ototoxicity and improve clinical care for NICU infants are discussed.
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26
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Ding D, Allman BL, Salvi R. Review: ototoxic characteristics of platinum antitumor drugs. Anat Rec (Hoboken) 2012; 295:1851-67. [PMID: 23044998 DOI: 10.1002/ar.22577] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Accepted: 07/24/2012] [Indexed: 11/10/2022]
Abstract
Cisplatin, carboplatin, nedaplatin, and oxaliplatin are widely used in contemporary oncology; however, their ototoxic and neurotoxic side effects are quite different as discussed in this review. Cisplatin is considered the most ototoxic, but despite its reputation, the magnitude of hair cell loss that occurs with a single, large drug bolus is limited and confined to the base of the cochlea. For all of these platinum compounds, a major factor limiting damage is drug uptake from stria vascularis into the cochlear fluids. Disrupting the blood-labyrinth barrier with diuretics or noise exposure enhances drug uptake and significantly increases the amount of damage. Combined treatment with ethacrynic acid (a loop diuretic) and cisplatin results in rapid apoptotic hair cell death characterized by upregulation of initiator caspase-8 and membrane death receptor, TRADD, followed by downstream executioners, caspase-3 and caspase-6. Unlike cisplatin, nedaplatin and oxaliplatin are highly neurotoxic when applied to cochlear cultures preferentially damaging auditory nerve fibers at low concentrations and hair cells at high concentrations. Carboplatin, considered far less ototoxic than cisplatin, is paradoxically highly toxic to chinchilla inner hair cells and type I spiral ganglion neurons; however, at high doses it also damages outer hair cells. Hair cell death from cisplatin and carboplatin is characterized in its early stages by upregulation of p53; blocking p53 expression with pifithrin-α prevents hair cell death. Major differences in the toxicity of these four platinum compounds may arise from several different metal transporters that selectively regulate the influx, efflux, and sequestration of these drugs.
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Affiliation(s)
- Dalian Ding
- Center for Hearing and Deafness, 137 Cary Hall, University at Buffalo, Buffalo, New York 14214, USA
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27
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FETONI A, ERAMO S, ROLESI R, TROIANI D, PALUDETTI G. Antioxidant treatment with coenzyme Q-ter in prevention of gentamycin ototoxicity in an animal model. ACTA OTORHINOLARYNGOLOGICA ITALICA : ORGANO UFFICIALE DELLA SOCIETA ITALIANA DI OTORINOLARINGOLOGIA E CHIRURGIA CERVICO-FACCIALE 2012; 32:103-10. [PMID: 22767971 PMCID: PMC3383078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2011] [Accepted: 12/22/2011] [Indexed: 11/18/2022]
Abstract
Aminoglycosides, such as gentamycin, are well known ototoxic agents. Toxicity occurs via an activation process involving the formation of an iron-gentamycin complex with free radical production. Antioxidants like Q-ter (a soluble formulation of coenzyme Q(10), CoQ(10)), can limit or prevent cellular ototoxic damage. The present study was designed to investigate the possible protective effects of Q-ter on gentamycin ototoxicity in albino guinea pigs (250-300 g). Animals were divided into five experimental groups: I, a sham control group given an intra-peritoneal (I.P.) injection of 0.5 ml saline (SHAM); II, gentamycin group (GM), treated with an injection of gentamycin (100 mg/ kg); III, gentamycin + Q-ter group (GM+Q-ter), treated with gentamycin (same dose as group II) and an I.P. injection of coenzyme Q(10) terclatrate (Q-ter) at 100 mg/kg body weight; IV, injected with gentamycin (100 mg/kg) plus saline; V, treated with Q-ter alone (100 mg/ kg). All animals were treated for 14 consecutive days. Auditory function was evaluated by recording auditory brainstem responses (ABR) at 15 and 30 days from the beginning of treatment. Morphological changes were analyzed by rhodamine-phalloidine staining. Gentamycin-induced progressive high-frequency hearing loss of 45-55 dB SPL. Q-ter therapy slowed and attenuated the progression of hearing loss, yielding a threshold shift of 20 dB. The significant loss of outer hair cells (OHCs) in the cochlear medio-basal turn in gentamycin-treated animals was not observed in the cochleae of animals protected with Q-ter. This study supports the hypothesis that Q-ter interferes with gentamycin-induced free radical formation, and suggests that it may be useful in protecting OHC function from aminoglycoside ototoxicity, thus reducing hearing loss.
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Affiliation(s)
| | - S.L.M. ERAMO
- Human Physiology, Catholic University of Rome, Italy
| | | | - D. TROIANI
- Human Physiology, Catholic University of Rome, Italy,Address for correspondence: Diana Troiani, Institute of Human Physiology, Catholic University of Rome, largo Francesco Vito 1, 00168 Rome, Italy. Tel. +39 06 30154966. E-mail:
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28
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Escobedo JO, Chu YH, Wang Q, Steyger PS, Strongin RM. Live cell imaging of a fluorescent gentamicin conjugate. Nat Prod Commun 2012; 7:317-320. [PMID: 22545403 PMCID: PMC3376166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023] Open
Abstract
Understanding cellular mechanisms of ototoxic and nephrotoxic drug uptake, intracellular distribution, and molecular trafficking across cellular barrier systems aids the study of potential uptake blockers that preserve sensory and renal function during critical life-saving therapy. Herein we report the design, synthesis characterization and evaluation of a fluorescent conjugate of the aminoglycoside antibiotic gentamicin. Live cell imaging results show the potential utility of this new material. Related gentamicin conjugates studied to date quench in live kindney cells, and have been largely restricted to use in fixed (delipidated) cells.
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Affiliation(s)
- Jorge O. Escobedo
- Department of Chemistry, Portland State University, Portland, OR, 97201, USA
| | - Yu-Hsuan Chu
- Department of Chemistry, Portland State University, Portland, OR, 97201, USA
| | - Qi Wang
- Oregon Hearing Research Center, Oregon Health & Science University, Portland, OR, 97239, USA
| | - Peter S. Steyger
- Oregon Hearing Research Center, Oregon Health & Science University, Portland, OR, 97239, USA
| | - Robert M. Strongin
- Department of Chemistry, Portland State University, Portland, OR, 97201, USA
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Li H, Steyger PS. Systemic aminoglycosides are trafficked via endolymph into cochlear hair cells. Sci Rep 2011; 1:159. [PMID: 22355674 PMCID: PMC3240991 DOI: 10.1038/srep00159] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2011] [Accepted: 10/31/2011] [Indexed: 11/24/2022] Open
Abstract
Aminoglycoside antibiotics rapidly enter and kill cochlear hair cells via apical mechanoelectrical transduction (MET) channels in vitro. In vivo, it remains unknown whether systemically-administered aminoglycosides cross the blood-labyrinth barrier into endolymph and enter hair cells. Here we show, for the first time, that systemic aminoglycosides are trafficked across the blood-endolymph barrier and preferentially enter hair cells across their apical membranes. This trafficking route is predominant compared to uptake via hair cell basolateral membranes during perilymph infusion.
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Affiliation(s)
- Hongzhe Li
- Oregon Hearing Research Center, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, Oregon 97239
| | - Peter S. Steyger
- Oregon Hearing Research Center, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, Oregon 97239
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