Transcript Mechanisms of aminoglycoside ototoxicity: opportunities for otoprotection – Corné Kros

Mechanisms of aminoglycoside ototoxicity:
opportunities for otoprotection
Corné Kros – [email protected]
Structure of the ear
From Tortora & Grabowski
Cochlear cultures as a model for studying hair cell
physiology and ototoxicity
Aminoglycoside antibiotics damage hair cells in vitro
•A: Outer hair cell damage
after exposure to 1 mM
neomycin for 1 hour
•B: Pre-treatment with the
Ca2+ chelator BAPTA (5
mM) prevents damage
How do aminoglycoside antibiotics damage hair cells?
•Aminoglycoside antibiotics (e.g.
dihydrostreptomycin) are bactericidal with
a broad anti-bacterial spectrum: used to
prevent or treat life-threatening infections
•Large, polycationic molecules enter
mechano-electrical transducer (MET)
channels
•Hearing damage occurs in 20-50% of
treated patients
•Oto- and nephro-toxic
•Trigger cell death through apoptosis
Recording MET currents in the mouse cochlea with a fluid jet
Kros, Rüsch & Richardson (1992) Proc R Soc
Extracellular DHS blocks MET currents at hyperpolarized
potentials
Marcotti, Van Netten & Kros (2005) J Physiol
Block by extracellular DHS is reduced at extreme positive
and also negative potentials: evidence of permeant block
Marcotti, Van Netten & Kros (2005) J Physiol
A model of the MET channel pore
DHS
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Van Netten & Kros (2007) in Curr Topics Membr 59
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Otoprotection strategies with competing, non-toxic
transducer channel blockers can be considered
Van Netten & Kros (2007) in Curr Topics Membr 59
In the cochlea the styryl dye FM1-43 selectively labels
hair cells
•Basal end
•high-freq
•more mature
•Apical end
•low-freq
•immature
FM1-43 protects hair cells from damage by aminoglycoside
antibiotics
1 mM neomycin
Control
1 mM neomycin
5 mM BAPTA pre
1 mM neomycin
30 M FM1-43
30 M FM1-43 pre
1 mM neomycin
How to try and get this funded as a research programme?
•Collaborate, both within institution and with external
partners
•Show you can do it: plenty of preliminary experiments
•Formulate realistic aims
•Work out detailed timeline and plan for experiments and
publication of results
•Carefully consider pathways to impact:
•Hearing research community
•Medicine
•Pharmaceutical industry
•Don’t underestimate time needed to hone the proposal:
one year between outline and submission of full proposal