The Experts below are selected from a list of 285 Experts worldwide ranked by ideXlab platform
David W. Raible - One of the best experts on this subject based on the ideXlab platform.
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Profiling drug-induced cell death pathways in the zebrafish lateral line
Apoptosis, 2013Co-Authors: Allison B. Coffin, Kay L. Williamson, Anna Mamiya, David W. Raible, Edwin W. RubelAbstract:Programmed cell death (PCD) is an important process in development and disease, as it allows the body to rid itself of unwanted or damaged cells. However, PCD pathways can also be activated in otherwise healthy cells. One such case occurs in sensory hair cells of the inner ear following exposure to Ototoxic drugs, resulting in hearing loss and/or balance disorders. The intracellular pathways that determine if hair cells die or survive following this or other Ototoxic challenges are incompletely understood. We use the larval zebrafish lateral line, an external hair cell-bearing sensory system, as a platform for profiling cell death pathways activated in response to Ototoxic stimuli. In this report the importance of each pathway was assessed by screening a custom cell death inhibitor library for instances when pathway inhibition protected hair cells from the aminoglycosides neomycin or gentamicin, or the chemotherapy agent cisplatin. This screen revealed that each ototoxin likely activated a distinct subset of possible cell death pathways. For example, the proteasome inhibitor Z-LLF-CHO protected hair cells from either aminoglycoside or from cisplatin, while d -methionine, an antioxidant, protected hair cells from gentamicin or cisplatin but not from neomycin toxicity. The calpain inhibitor leupeptin primarily protected hair cells from neomycin, as did a Bax channel blocker. Neither caspase inhibition nor protein synthesis inhibition altered the progression of hair cell death. Taken together, these results suggest that ototoxin-treated hair cells die via multiple processes that form an interactive network of cell death signaling cascades.
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proliferative regeneration of zebrafish lateral line hair cells after different Ototoxic insults
PLOS ONE, 2012Co-Authors: Scott M Mackenzie, David W. RaibleAbstract:Sensory hair cells in the zebrafish lateral line regenerate rapidly and completely after damage. Previous studies have used a variety of ototoxins to kill lateral line hair cells to study different phenomena including mechanisms of hair cell death and regeneration. We sought to directly compare these ototoxins to determine if they differentially affected the rate and amount of hair cell replacement. In addition, previous studies have found evidence of proliferative hair cell regeneration in zebrafish, but both proliferation and non-mitotic direct transdifferentiation have been observed during hair cell regeneration in the sensory epithelia of birds and amphibians. We sought to test whether a similar combination of regenerative mechanisms exist in the fish. We analyzed the time course of regeneration after treatment with different Ototoxic compounds and also labeled dividing hair cell progenitors. Certain treatments, including cisplatin and higher concentrations of dissolved copper, significantly delayed regeneration by one or more days. However, cisplatin did not block all regeneration as observed previously in the chick basilar papilla. The particular ototoxin did not appear to affect the mechanism of regeneration, as we observed evidence of recent proliferation in the majority of new hair cells in all cases. Inhibiting proliferation with flubendazole blocked the production of new hair cells and prevented the accumulation of additional precursors, indicating that proliferation has a dominant role during regeneration of lateral line hair cells.
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Using the Zebrafish Lateral Line to Screen for Ototoxicity
Journal of the Association for Research in Otolaryngology, 2008Co-Authors: Lynn L. Chiu, David W. Raible, Edwin W. Rubel, Lisa L. Cunningham, Henry C. OuAbstract:The zebrafish is a valuable model for studying hair cell development, structure, genetics, and behavior. Zebrafish and other aquatic vertebrates have hair cells on their body surface organized into a sensory system called the lateral line. These hair cells are highly accessible and easily visualized using fluorescent dyes. Morphological and functional similarities to mammalian hair cells of the inner ear make the zebrafish a powerful preparation for studying hair cell toxicity. The Ototoxic potential of drugs has historically been uncovered by anecdotal reports that have led to more formal investigation. Currently, no standard screen for Ototoxicity exists in drug development. Thus, for the vast majority of Food and Drug Association (FDA)-approved drugs, the Ototoxic potential remains unknown. In this study, we used 5-day-old zebrafish larvae to screen a library of 1,040 FDA-approved drugs and bioactives (NINDS Custom Collection II) for Ototoxic effects in hair cells of the lateral line. Hair cell nuclei were selectively labeled using a fluorescent vital dye. For the initial screen, fish were exposed to drugs from the library at a 100-μM concentration for 1 h in 96-well tissue culture plates. Hair cell viability was assessed in vivo using fluorescence microscopy. One thousand forty drugs were rapidly screened for Ototoxic effects. Seven known Ototoxic drugs included in the library, including neomycin and cisplatin, were positively identified using these methods, as proof of concept. Fourteen compounds without previously known Ototoxicity were discovered to be selectively toxic to hair cells. Dose–response curves for all 21 Ototoxic compounds were determined by quantifying hair cell survival as a function of drug concentration. Dose–response relationships in the mammalian inner ear for two of the compounds without known Ototoxicity, pentamidine isethionate and propantheline bromide, were then examined using in vitro preparations of the adult mouse utricle. Significant dose-dependent hair cell loss in the mouse utricle was demonstrated for both compounds. This study represents an important step in validating the use of the zebrafish lateral line as a screening tool for the identification of potentially Ototoxic drugs.
Lisa L. Cunningham - One of the best experts on this subject based on the ideXlab platform.
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non autonomous cellular responses to Ototoxic drug induced stress and death
Frontiers in Cellular Neuroscience, 2017Co-Authors: Shimon P Francis, Lisa L. CunninghamAbstract:The first major recognition of drug-induced hearing loss can be traced back more than seven decades to the development of streptomycin as an antimicrobial agent. Since then at least 130 therapeutic drugs have been recognized as having Ototoxic side- effects. Two important classes of Ototoxic drugs are the aminoglycoside antibiotics and the antineoplastic agent cisplatin. These drugs save the lives of millions of people worldwide, but they also cause irreparable hearing loss. In the inner ear, sensory hair cells (HCs) and spiral ganglion neurons (SGNs) are important cellular targets of these drugs, and most mechanistic studies have focused on the cell-autonomous responses of these cell types in response to Ototoxic stress. Despite several decades of studies on Ototoxicity, important unanswered questions remain, including the cellular and molecular mechanisms that determine whether HCs and SGNs will live or die when confronted with Ototoxic challenge. Emerging evidence indicates that other cell types in the inner ear can act as mediators of survival or death of sensory cells and spiral ganglion neurons. For example, glia-like supporting cells (SCs) can promote survival of both HCs and SGNs. Alternatively, SCs can act to promote HC death and inhibit neural fiber expansion. Similarly, tissue resident macrophages activate either pro-survival or pro-death signaling that can influence HC survival after exposure to Ototoxic agents. Together these data indicate that autonomous responses that occur within a stressed HC or SGN are not the only (and possibly not the primary) determinants of whether the stressed cell ultimately lives or dies. Instead non-autonomous cellular responses are emerging as significant determinants of HC and SGN survival vs. death in the face of Ototoxic stress. The goal of this review is to summarize the current evidence on non-autonomous cellular responses to Ototoxic stress and to discuss ways in which this knowledge may advance the development of therapies to reduce hearing loss caused by these drugs.
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sound preconditioning therapy inhibits Ototoxic hearing loss in mice
Journal of Clinical Investigation, 2013Co-Authors: Soumen Roy, Matthew Ryals, Astrid Botty Van Den Bruele, Tracy S Fitzgerald, Lisa L. CunninghamAbstract:Therapeutic drugs with Ototoxic side effects cause significant hearing loss for thousands of patients annually. Two major classes of Ototoxic drugs are cisplatin and the aminoglycoside antibiotics, both of which are toxic to mechanosensory hair cells, the receptor cells of the inner ear. A critical need exists for therapies that protect the inner ear without inhibiting the therapeutic efficacy of these drugs. The induction of heat shock proteins (HSPs) inhibits both aminoglycoside- and cisplatin-induced hair cell death and hearing loss. We hypothesized that exposure to sound that is titrated to stress the inner ear without causing permanent damage would induce HSPs in the cochlea and inhibit Ototoxic drug–induced hearing loss. We developed a sound exposure protocol that induces HSPs without causing permanent hearing loss. We used this protocol in conjunction with a newly developed mouse model of cisplatin Ototoxicity and found that preconditioning mouse inner ears with sound has a robust protective effect against cisplatin-induced hearing loss and hair cell death. Sound therapy also provided protection against aminoglycoside-induced hearing loss. These data indicate that sound preconditioning protects against both classes of Ototoxic drugs, and they suggest that sound therapy holds promise for preventing hearing loss in patients receiving these drugs.
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celastrol inhibits aminoglycoside induced Ototoxicity via heat shock protein 32
Cell Death and Disease, 2011Co-Authors: Shimon P Francis, I I Kramarenko, Carlene S Brandon, Fushing Lee, Tiffany G Baker, Lisa L. CunninghamAbstract:Hearing loss is often caused by death of the mechanosensory hair cells of the inner ear. Hair cells are susceptible to death caused by aging, noise trauma, and Ototoxic drugs, including the aminoglycoside antibiotics and the antineoplastic agent cisplatin. Ototoxic drugs result in permanent hearing loss for over 500,000 Americans annually. We showed previously that induction of heat shock proteins (HSPs) inhibits both aminoglycoside- and cisplatin-induced hair cell death in whole-organ cultures of utricles from adult mice. In order to begin to translate these findings into a clinical therapy aimed at inhibiting Ototoxic drug-induced hearing loss, we have now examined a pharmacological HSP inducer, celastrol. Celastrol induced upregulation of HSPs in utricles, and it provided significant protection against aminoglycoside-induced hair cell death in vitro and in vivo. Moreover, celastrol inhibited hearing loss in mice receiving systemic aminoglycoside treatment. Our data indicate that the major heat shock transcription factor HSF-1 is not required for celastrol-mediated protection. HSP32 (also called heme oxygenase-1, HO-1) is the primary mediator of the protective effect of celastrol. HSP32/HO-1 inhibits pro-apoptotic c-Jun N-terminal kinase (JNK) activation and hair cell death. Taken together, our data indicate that celastrol inhibits aminoglycoside Ototoxicity via HSP32/HO-1 induction.
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Using the Zebrafish Lateral Line to Screen for Ototoxicity
Journal of the Association for Research in Otolaryngology, 2008Co-Authors: Lynn L. Chiu, David W. Raible, Edwin W. Rubel, Lisa L. Cunningham, Henry C. OuAbstract:The zebrafish is a valuable model for studying hair cell development, structure, genetics, and behavior. Zebrafish and other aquatic vertebrates have hair cells on their body surface organized into a sensory system called the lateral line. These hair cells are highly accessible and easily visualized using fluorescent dyes. Morphological and functional similarities to mammalian hair cells of the inner ear make the zebrafish a powerful preparation for studying hair cell toxicity. The Ototoxic potential of drugs has historically been uncovered by anecdotal reports that have led to more formal investigation. Currently, no standard screen for Ototoxicity exists in drug development. Thus, for the vast majority of Food and Drug Association (FDA)-approved drugs, the Ototoxic potential remains unknown. In this study, we used 5-day-old zebrafish larvae to screen a library of 1,040 FDA-approved drugs and bioactives (NINDS Custom Collection II) for Ototoxic effects in hair cells of the lateral line. Hair cell nuclei were selectively labeled using a fluorescent vital dye. For the initial screen, fish were exposed to drugs from the library at a 100-μM concentration for 1 h in 96-well tissue culture plates. Hair cell viability was assessed in vivo using fluorescence microscopy. One thousand forty drugs were rapidly screened for Ototoxic effects. Seven known Ototoxic drugs included in the library, including neomycin and cisplatin, were positively identified using these methods, as proof of concept. Fourteen compounds without previously known Ototoxicity were discovered to be selectively toxic to hair cells. Dose–response curves for all 21 Ototoxic compounds were determined by quantifying hair cell survival as a function of drug concentration. Dose–response relationships in the mammalian inner ear for two of the compounds without known Ototoxicity, pentamidine isethionate and propantheline bromide, were then examined using in vitro preparations of the adult mouse utricle. Significant dose-dependent hair cell loss in the mouse utricle was demonstrated for both compounds. This study represents an important step in validating the use of the zebrafish lateral line as a screening tool for the identification of potentially Ototoxic drugs.
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the adult mouse utricle as an in vitro preparation for studies of Ototoxic drug induced sensory hair cell death
Brain Research, 2006Co-Authors: Lisa L. CunninghamAbstract:Sensory hair cells of the inner ear are susceptible to death from a variety of stresses including aging, noise trauma, genetic disorders, and exposure to certain therapeutic drugs. Ototoxic drugs include the aminoglycoside antibiotics and the antineoplastic agent cisplatin. This is a short technical report describing the dissection and culture of the adult mouse utricle. This in vitro preparation allows for detailed studies of Ototoxic-drug-induced hair cell death in an adult mammalian system. In addition, this preparation allows for examination of the effects of specific gene products through the use of transgenic and knockout mouse models.
Shiming Yang - One of the best experts on this subject based on the ideXlab platform.
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unitary Ototoxic gentamicin exposure may not disrupt the function of cochlear outer hair cells in mice
Acta Oto-laryngologica, 2017Co-Authors: Ning Zhao, Daishi Chen, Shiming Yang, Bo Yang, Lin Shi, Xuhui Tai, Lijie Zhai, Kun Hou, Shusheng Gong, Ke LiuAbstract:BACKGROUND Previous study showed that mild Ototoxic exposure could induce a reversible hearing impairment, and the loss and secondary incomplete recovery of cochlear ribbon synapses could be responsible for the hearing loss. However, it remains unclear whether cochlear outer hair cells' (OHCs) functions are affected. OBJECTIVE To verify whether the function of OHCs are also affected significantly after the Ototoxic exposure. METHODS Mice were injected intraperitoneally with 100 mg/kg concentration of gentamicin daily for 14 days. Distortion Product of Oto-acoustic Emission (DPOAE) was detected at control (pre-treatment), Day 0, day 4, day 7, day 14 and day 28 after the Ototoxic exposure, respectively. In addition, the morphology of OHCs was observed by electron microscopy, OHCs has been counted by light microscopy, and the hearing thresholds were detected by auditory brain response (ABR). RESULTS No significant changes have been found in OHC and OHC stereocilia among the experimental groups (p > .05). Further, no significant changes or loss was found in the morphology of OHCs either. However, we found ABR threshold elevations occurred after Ototoxic exposure. CONCLUSIONS Unitary Ototoxic gentamicin exposure may not disrupt the function of cochlear OHCs in mice, regardless of hearing loss identified in this Ototoxic exposure.
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spontaneous and partial repair of ribbon synapse in cochlear inner hair cells after Ototoxic withdrawal
Molecular Neurobiology, 2015Co-Authors: Ke Liu, Daishi Chen, Weiwei Guo, Xiaoyu Wang, Zhaohui Hou, Weiyan Yang, Shiming YangAbstract:Ototoxicity is one of the major causes of sensorineural deafness. However, it remains unclear whether sensorineural deafness is reversible after Ototoxic withdrawal. Here, we report that the ribbon synapses between the inner hair cells (IHCs) and spiral ganglion nerve (SGN) fibers can be restored after Ototoxic trauma. This corresponds with hearing restoration after Ototoxic withdrawal. In this study, adult mice were injected daily with a low dose of gentamicin for 14 consecutive days. Immunostaining for RIBEYE/CtBP2 was used to estimate the number and size of synaptic ribbons in the cochlea. Hearing thresholds were assessed using auditory brainstem responses. Auditory temporal processing between IHCs and SGNs was evaluated by compound action potentials. We found automatic hearing restoration after Ototoxicity withdrawal, which corresponded to the number and size recovery of synaptic ribbons, although both hearing and synaptic recovery were not complete. Thus, our study indicates that sensorineural deafness in mice can be reversible after Ototoxic withdrawal due to an intrinsic repair of ribbon synapse in the cochlea.
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Cochlear Inner Hair Cell Ribbon Synapse is the Primary Target of Ototoxic Aminoglycoside Stimuli
Molecular neurobiology, 2013Co-Authors: Ke Liu, Weiyan Yang, Bo Yang, Xuejun Jiang, Chuang Shi, Lei Shi, Lin Shi, Shiming YangAbstract:The ribbon synapses of inner hair cells (IHCs) play an important role in sound encoding and neurotransmitter release. However, it remains unclear whether IHC ribbon synapse plasticity can be interrupted by Ototoxic aminoglycoside stimuli. Here, we report that quantitative changes in the number of IHC ribbon synapses and hearing loss occur in response to gentamicin treatment in mice. Using 3D reconstruction, we were able to calculate the number of IHC ribbon synapses after Ototoxic gentamicin exposure. Mice were injected intraperitoneally with a low dose of gentamicin (100 mg/kg) once a day for 14 days. Double immunostaining was used to identify IHC ribbon synapses; histopathology and scanning electron microscopy were used to observe the morphology of cochlear hair cells and spiral ganglion neurons (SGNs), the hearing threshold shifts were recorded by auditory brainstem response examinations. Our study shows that the maximal number of IHC ribbon synapses appeared at the 7th day after treatment, followed by a significant reduction after the 7th day regardless of ongoing treatment. Correspondingly, the maximal elevation of hearing threshold was observed at the 7th day after treatment. Meanwhile, additional cochlear components included OHCs, IHCs, and SGNs were unaffected, suggesting that IHC ribbon synapses are more susceptible to Ototoxic aminoglycoside stimulation. Our study indicated that quantitative changes in the number of IHC ribbon synapses is critical response to lower dose of Ototoxic stimulation, and may contribute to moderate hearing loss. Additionally, our data indcated that ribbon synaptic plasticity may require the quantitative changes to play self-protective role adapted to Ototoxic aminoglycoside stimuli.
Edwin W. Rubel - One of the best experts on this subject based on the ideXlab platform.
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Profiling drug-induced cell death pathways in the zebrafish lateral line
Apoptosis, 2013Co-Authors: Allison B. Coffin, Kay L. Williamson, Anna Mamiya, David W. Raible, Edwin W. RubelAbstract:Programmed cell death (PCD) is an important process in development and disease, as it allows the body to rid itself of unwanted or damaged cells. However, PCD pathways can also be activated in otherwise healthy cells. One such case occurs in sensory hair cells of the inner ear following exposure to Ototoxic drugs, resulting in hearing loss and/or balance disorders. The intracellular pathways that determine if hair cells die or survive following this or other Ototoxic challenges are incompletely understood. We use the larval zebrafish lateral line, an external hair cell-bearing sensory system, as a platform for profiling cell death pathways activated in response to Ototoxic stimuli. In this report the importance of each pathway was assessed by screening a custom cell death inhibitor library for instances when pathway inhibition protected hair cells from the aminoglycosides neomycin or gentamicin, or the chemotherapy agent cisplatin. This screen revealed that each ototoxin likely activated a distinct subset of possible cell death pathways. For example, the proteasome inhibitor Z-LLF-CHO protected hair cells from either aminoglycoside or from cisplatin, while d -methionine, an antioxidant, protected hair cells from gentamicin or cisplatin but not from neomycin toxicity. The calpain inhibitor leupeptin primarily protected hair cells from neomycin, as did a Bax channel blocker. Neither caspase inhibition nor protein synthesis inhibition altered the progression of hair cell death. Taken together, these results suggest that ototoxin-treated hair cells die via multiple processes that form an interactive network of cell death signaling cascades.
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Using the Zebrafish Lateral Line to Screen for Ototoxicity
Journal of the Association for Research in Otolaryngology, 2008Co-Authors: Lynn L. Chiu, David W. Raible, Edwin W. Rubel, Lisa L. Cunningham, Henry C. OuAbstract:The zebrafish is a valuable model for studying hair cell development, structure, genetics, and behavior. Zebrafish and other aquatic vertebrates have hair cells on their body surface organized into a sensory system called the lateral line. These hair cells are highly accessible and easily visualized using fluorescent dyes. Morphological and functional similarities to mammalian hair cells of the inner ear make the zebrafish a powerful preparation for studying hair cell toxicity. The Ototoxic potential of drugs has historically been uncovered by anecdotal reports that have led to more formal investigation. Currently, no standard screen for Ototoxicity exists in drug development. Thus, for the vast majority of Food and Drug Association (FDA)-approved drugs, the Ototoxic potential remains unknown. In this study, we used 5-day-old zebrafish larvae to screen a library of 1,040 FDA-approved drugs and bioactives (NINDS Custom Collection II) for Ototoxic effects in hair cells of the lateral line. Hair cell nuclei were selectively labeled using a fluorescent vital dye. For the initial screen, fish were exposed to drugs from the library at a 100-μM concentration for 1 h in 96-well tissue culture plates. Hair cell viability was assessed in vivo using fluorescence microscopy. One thousand forty drugs were rapidly screened for Ototoxic effects. Seven known Ototoxic drugs included in the library, including neomycin and cisplatin, were positively identified using these methods, as proof of concept. Fourteen compounds without previously known Ototoxicity were discovered to be selectively toxic to hair cells. Dose–response curves for all 21 Ototoxic compounds were determined by quantifying hair cell survival as a function of drug concentration. Dose–response relationships in the mammalian inner ear for two of the compounds without known Ototoxicity, pentamidine isethionate and propantheline bromide, were then examined using in vitro preparations of the adult mouse utricle. Significant dose-dependent hair cell loss in the mouse utricle was demonstrated for both compounds. This study represents an important step in validating the use of the zebrafish lateral line as a screening tool for the identification of potentially Ototoxic drugs.
Lavinia Sheets - One of the best experts on this subject based on the ideXlab platform.
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macrophages respond rapidly to Ototoxic injury of lateral line hair cells but are not required for hair cell regeneration
Frontiers in Cellular Neuroscience, 2021Co-Authors: Mark E Warchol, Angela Schrader, Lavinia SheetsAbstract:The sensory organs of the inner ear contain resident populations of macrophages, which are recruited to sites of cellular injury. Such macrophages are known to phagocytose the debris of dying cells but the full role of macrophages in otic pathology is not understood. Lateral line neuromasts of zebrafish contain hair cells that are nearly identical to those in the inner ear, and the optical clarity of larval zebrafish permits direct imaging of cellular interactions. In this study, we used larval zebrafish to characterize the response of macrophages to Ototoxic injury of lateral line hair cells. Macrophages migrated into neuromasts within 20 min of exposure to the Ototoxic antibiotic neomycin. The number of macrophages in the near vicinity of injured neuromasts was similar to that observed near uninjured neuromasts, suggesting that this early inflammatory response was mediated by "local" macrophages. Upon entering injured neuromasts, macrophages actively phagocytosed hair cell debris. The injury-evoked migration of macrophages was significantly reduced by inhibition of Src-family kinases. Using chemical-genetic ablation of macrophages before the Ototoxic injury, we also examined whether macrophages were essential for the initiation of hair cell regeneration. Results revealed only minor differences in hair cell recovery in macrophage-depleted vs. control fish, suggesting that macrophages are not essential for the regeneration of lateral line hair cells.
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macrophages respond rapidly to Ototoxic injury of lateral line hair cells but are not required for hair cell regeneration
bioRxiv, 2020Co-Authors: Mark E Warchol, Angela Schrader, Lavinia SheetsAbstract:Abstract The sensory organs of the inner ear contain resident populations of macrophages, which are recruited to sites of cellular injury. Such macrophages are known to phagocytose the debris of dying cells but the full role of macrophages in otic pathology is not understood. Lateral line neuromasts of zebrafish contain hair cells similar to those in the inner ear, and the optical clarity of larval zebrafish permits direct imaging of cellular interactions. In this study, we used larval zebrafish to characterize the response of macrophages to Ototoxic injury of lateral line hair cells. Macrophages migrated into neuromasts within 20 min of exposure to the Ototoxic antibiotic neomycin. The number of macrophages in close proximity of injured neuromasts was similar to that observed near uninjured neuromasts, suggesting that this early inflammatory response was mediated by ‘local’ macrophages. Upon entering injured neuromasts, macrophages actively phagocytosed hair cell debris. Such phagocytosis was significantly reduced by inhibiting Src-family kinases. Using chemical-genetic ablation of macrophages prior to Ototoxic injury, we also examined whether macrophages were essential for the initiation of hair cell regeneration after neomycin exposure. Results revealed only minor differences in hair cell recovery in macrophage-depleted vs. control fish, suggesting that macrophages are not essential for the regeneration of lateral line hair cells.
