Identification of ion-channel modulators that protect against aminoglycoside-induced hair cell death
Emma J. Kenyon, Nerissa K. Kirkwood, Siân R. Kitcher, Molly O’Reilly, Marco Derudas, Daire M. Cantillon, Richard J. Goodyear, Abigail Secker, Sarah Baxendale, James C. Bull, Simon J. Waddell, Tanya T. Whitfield, Simon E. Ward, Corné J. Kros, Guy P. Richardson
Emma J. Kenyon, Nerissa K. Kirkwood, Siân R. Kitcher, Molly O’Reilly, Marco Derudas, Daire M. Cantillon, Richard J. Goodyear, Abigail Secker, Sarah Baxendale, James C. Bull, Simon J. Waddell, Tanya T. Whitfield, Simon E. Ward, Corné J. Kros, Guy P. Richardson
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Research Article Neuroscience

Identification of ion-channel modulators that protect against aminoglycoside-induced hair cell death

Abstract

Aminoglycoside antibiotics are used to treat life-threatening bacterial infections but can cause deafness due to hair cell death in the inner ear. Compounds have been described that protect zebrafish lateral line hair cells from aminoglycosides, but few are effective in the cochlea. As the aminoglycosides interact with several ion channels, including the mechanoelectrical transducer (MET) channels by which they can enter hair cells, we screened 160 ion-channel modulators, seeking compounds that protect cochlear outer hair cells (OHCs) from aminoglycoside-induced death in vitro. Using zebrafish, 72 compounds were identified that either reduced loading of the MET-channel blocker FM 1-43FX, decreased Texas red–conjugated neomycin labeling, or reduced neomycin-induced hair cell death. After testing these 72 compounds, and 6 structurally similar compounds that failed in zebrafish, 13 were found that protected against gentamicin-induced death of OHCs in mouse cochlear cultures, 6 of which are permeant blockers of the hair cell MET channel. None of these compounds abrogated aminoglycoside antibacterial efficacy. By selecting those without adverse effects at high concentrations, 5 emerged as leads for developing pharmaceutical otoprotectants to alleviate an increasing clinical problem.

Authors

Emma J. Kenyon, Nerissa K. Kirkwood, Siân R. Kitcher, Molly O’Reilly, Marco Derudas, Daire M. Cantillon, Richard J. Goodyear, Abigail Secker, Sarah Baxendale, James C. Bull, Simon J. Waddell, Tanya T. Whitfield, Simon E. Ward, Corné J. Kros, Guy P. Richardson

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Figure 4

Compounds providing protection against 5 μM gentamicin at low concentrations.

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Compounds providing protection against 5 μM gentamicin at low concentrat...
Cultures prepared from P2 pups were treated with (A) 0.5% DMSO (n = 67), (B) 5 μM gentamicin (n = 67), 5 μM gentamicin and 13143 at (C) 5 μM (n = 5), (E) 3 μM (n = 5), (G) 1 μM (n = 4), and (I) 0.5 μM (n = 3) or 5 μM gentamicin and 13097 at (D) 30 nM (n = 5), (F) 10 nM (n = 5), (H) 3 nM (n = 4), and (J) 1 nM (n = 4) (numbers of independent tests are shown after each compound number). Cultures were labeled with TRITC-phalloidin. Images in A and B are representative of 67 experiments. Images in C–J are representative of 3–5 experiments. (K) Dose-response curves showing the percentage survival of basal-coil OHCs in cultures treated with gentamicin and either compound 13097 (red) or compound 13143 (blue) compared with that in control cultures. Error bars are SEM from 3–8 independent tests. Curves are fit to the equation: OHC survival (%) = B + (100–B)[C]/(K + [C]), where B is the percentage of OHCs surviving in gentamicin alone, [C] is the concentration of the compound, and K is the compound concentration at which 50% protection occurs. For 13097, K = 4.9 nM and B = 12.6%; for 13143, K = 840 nM and B = 11.5%. Scale bar: 50 μm.