ESCMID Online Lecture Library. by author

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1 Neurologische Klinik und Poliklinik Prof. Dr. M. Dieterich Animal models of meningitis-associated hearing loss M Klein, Siena 5/2012

2 Hearing Loss is common in survivors of Pneumococcal Meningitis oedema ischemia hydrocephalus venous thrombosis Hearing loss in 26% of survivors bleeding 25 (29%) 19 (22%) 14 (16%) 9 (10%) 8 (9%) Brain 2003

3 Overview Meningitis-associated hearing loss in humans Overview of temporal bone anatomy Animal models to study meningitis-associated hearing loss Tools to study Hearing in animals (with meningitis) Histomorphologic correlates of meningitis-associated hearing loss Studying Mechanisms of Damage Adjunctive Therapeutic Options of Meningitis-associated Hearing Loss Summary

4 Hearing Loss is common in survivors of Pneumococcal Meningitis 63 studies, 3408 survivors of pneumococcal meningitis Journal of Infection 2010

5 Clinical characteristics of Meningitis-associated Hearing Loss most common long term sequelae uni- or bilateral mild to severe early onset partially reversible problems at school or at work social problems difficulties in development of behavior and speech recognition

6 Site of the lesion of meningitis-associated hearing loss: the cochlea. Am J Otol 1996

7 Starring The Cochlea

8 Apex Modiolus (Cochlear Nerv) Starring The Cochlea Basal turn

9 Starring The Cochlea Modiolus Scala vestibuli Ganglion Scala media Organ of Corti Scala tympani

10 Overview Meningitis-associated hearing loss in humans Overview of temporal bone anatomy Animal models to study meningitis-associated hearing loss Tools to study hearing in animals (with meningitis) Histomorphologic correlates of meningitis-associated hearing loss Studying Mechanisms of Damage Adjunctive Therapeutic Options of Meningitis-associated Hearing Loss Summary

11 intrathecal infection direct cochlear perfusion Tools to study hearing impairment in meningitis Animals: rabbits, guinea pig, gerbil, mouse Pathogen: S. pneumoniae E. coli H. influenzae S. suis Hearing assessment: Auditory brainstem responses Otoacustic emissions (Cochlear action potential, Microphonic potential) Cochlear Assessment: Light microscopy (structural damage) Electrone microscopy (ultrastructural damage)

12 Methods to measure Hearing Loss in Animals: Auditory Brainstem Responses

13 Stimulus (Klick, 1kHz, 10kHz) Intensity: 10dB SPL 130dB SPL Hearing assessment in rodents: Auditory Brainstem Responses (ABRs) 250,000x amplification Averaging of 1000 responses Healthy Mouse Time after stimulus (ms) Mouse with Meningitis Ketamine / Xylazine sedation Klein et al., Brain Pathology 2003 Time after stimulus (ms)

14 Hearing assessment in rodents: Auditory Brainstem Responses (ABRs) + exact measurement of hearing thresholds + assesses post-cochlear structures +/- preselected single frequencies - time consuming Klein et al., Brain Pathology 2003 Healthy Mouse Time after stimulus (ms) Mouse with Meningitis Time after stimulus (ms)

15 Hearing assessment in rodents: Otoacustic Emissions Mechanism of Otoacustic Emissions: Sound leads to tension of hair cells (to increase signal), eliciting movement of the Reissner Membrane which makes a minimal sound that can be detected by a microphone.

16 Brandt et al., Neurobiology of Disease 2006 Hearing assessment in rodents: Otoacustic Emissions Speaker plus Microphone + quick + covers whole frequency spectrum - poor cut off Frequency Healthy Rat Rat with Meningitis

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18 First animal model of Hearing Loss in pneumococcal Meningitis Rabbits Streptococcus pneumoniae type III CFU, intracisternal Auditory brainstem response q12h Laryngoscope1991

19 Wistar rats Streptococcus pneumoniae type III intracisternal infection Auditory brainstem response Development of Hearing Loss in experimental Meningitis Otolaryngol Head Neck Surg 1999

20 Time Course of Hearing Loss in experimental Meningitis after treatment Wistar rats Streptococcus pneumoniae type III Intracisternal infection Auditory brainstem response Treatment of animals with ceftriaxone starting 24h p.i. Hearing loss (db) * Ceftriaxone * * # # * * # Time after infection (h) Control * # Klein et et al., al., Brain Brain Pathol., Pathol

21 Overview Meningitis-associated hearing loss in humans Overview of temporal bone anatomy Animal models to study meningitis-associated hearing loss Tools to study hearing in animals (with meningitis) Histomorphologic correlates of meningitis-associated hearing loss Studying Mechanisms of Damage Adjunctive Therapeutic Options of Meningitis-associated Hearing Loss Summary

22 Human Histomorphological correlates of Meningitis acute stage: suppurative labyrinthitis Meningitis Meningitis Rabbit Meningitis Meningitis Control Rat Mouse Bhatt et al., 1991, Brandt et al., 2006, Klein et al., 2007, Merchant et al., 1996

23 Spread of infection through the cochlear aqueduct Cochlear aqueduct = perilymphatic duct Laryngoscope 2009

24 Histomorphological correlates of Meningitis acute stage: hair cell damage Control Acute meningitis

25 Histomorphological correlates of Meningitis acute stage: hair cell damage Rabbits E. coli, Haemophilus influenzae type B Intracisternal infection Auditory brainstem response Electrone microscopy: Hair Cells Int J Exp Pathol 1995

26 Histomorphological correlates of Meningitis acute stage: blood labyrinth barrier damage Evans Blue MRI of a patient with pneumococcal meningitis 1h Kastenbauer and Klein et al., Brain Res 2001

27 Histomorphologic correlates of meningitis-associated hearing loss: late stage fibrocytic occlusion Parparella 1976 labyrinthitis ossificans Merchant et al neuronal loss neuronal loss Klein et al., Brain Pathol 2003

28 Studying cochlear ossification after meningitis Mongolian gerbils Streptococcus pneumoniae intrathecal infection Treatment with Penicillin G day 1-8 Administration of Fluorochrome Labes Investigation of cochleae from 24h to 12 months after infection S. vestibuli S. tympani Nabili et al., Laryngoscope 1999, Tinling et al., Laryngoscope 2004

29 Mouse Control Neuronal loss after meningitis Meningitis Human Meningitis Healthy Klein et al, J Infect Dis 2007

30 Mouse Control Neuronal loss after meningitis Meningitis South of England Cochlear Implant Centre Intact neurons are crucial for functioning of cochlear implants Klein et al, J Infect Dis 2007

31 Hair cell loss after meningitis Control Acute meningitis 2 weeks p.i. Klein et al, J Infect Dis 2007

32 degree of hearing loss Histologic observations - summary Onset Acute stage After recovery antibiotic therapy suppurative labyrinthitis fibrocytic occlusion blood-labyrinth barrier destruction hair cell damage labyrinthitis ossificans loss of the Organ of Corti spiral ganglion neuronal damage spiral ganglion neuronal loss

33 Overview Meningitis-associated hearing loss in humans Overview of temporal bone anatomy Animal models to study meningitis-associated hearing loss Tools to study hearing in animals (with meningitis) Histomorphologic correlates of meningitis-associated hearing loss Studying Mechanisms of Damage Adjunctive Therapeutic Options of Meningitis-associated Hearing Loss Summary

34 Histomorphologic correlates of meningitis-associated hearing loss: humans Rats Pretreatment with G-CSF Therapy with ceftriaxone Otoacustic emissions Histology Follow up 8 days Neurobiol of Dis 2006

35 Gram Stain infiziert WT Meningitis MyD88-/- Die Entzündungsreaktion ist entscheidend an der kochleären Schädigung beteiligt Hearing loss ( db SPL) ? Wildtyp MyD88-/- 1kHz * * 10kHz klick Nitrotyrosin nicht infiziert WT infiziert WT Klein et al., J Infect Dis (2007), 195: und Kastenbauer, Klein et al., Brain Res (2001), 904:

36 Acute oxidative stress in the cochlea S. pneumoniae D39 antioxidant adjunctive therapy with MnTBAP or N-Acetyl-L-Cystein (NAC) Hörverlust ( db SPL) nicht infiziert ** iinfiziert +Ceftriaxon + infiziert +Ceftriaxon + MnTBAP + * infected +Ceftriaxon + NAC Klein et al., Ann Neurol (2003), 54:

37 Gerbils Streptococcus pneumoniae type III Intracisternal infection Treatment with SOD intracisternally, middle ear infusion Follow Up at week 15 Hearing Loss ( db SPL) Acute oxidative stress in the cochlea Otol Neurotol 2008

38 H earing T hreshold (click stim ulus) Mouse Pneumolysin contributes to hearing loss 24h p.i. uninfected D39 D39 PLY infected D39 vs. D39 PLY (Pneumolysin deficient D39) Guinea Pigs D39 PLY D39 Klein et al., unpublished data Winter et al., Infect Immun 1997

39 Neurotrophin (after recovery) Spiral ganglion Pathophysiologic model of meningitis-associated hearing loss ONOO - Scala media Scala tympani Spiral ligament (blood-labyrinth barrier) ONOO - Pneumolysin ONOO - MyD88 Cochlear aqueaduct

40 Overview Meningitis-associated hearing loss in humans Overview of temporal bone anatomy Animal models to study meningitis-associated hearing loss Tools to study hearing in animals (with meningitis) Histomorphologic correlates of meningitis-associated hearing loss Studying Mechanisms of Damage Adjunctive Therapeutic Options of Meningitis-associated Hearing Loss Summary

41 Meningitis-associated hearing loss and adjunctive therapy Animal Adjunctive drug Effects on Year, Author Hearing Loss Cochlear Pathology Rabbit Dexamethasone* N.A. 1995, Bhatt et al. Rats Betamethasone (intratympanic) neuronal loss 2010, Worsoe et al. Infant Rats Dexamethasone neuronal loss 2009, Coimbra et al. Infant rats Doxycyclin neuronal loss 2006, Meli et al. Rat N-Acetyl-L-Cystein neuronal loss cochlear fibrosis Guinea Pigs SOD (local) neuronal loss cochlear fibrosis Infant Rats Mice 2003, Klein et al. 2004, Ge et al. Glycerol cochlear inflam. 2010, Blaser et al. Rats BDNF (local) N.A. 2005, Li et al. Mice Neurotrophin-3 neuronal loss cochlear fibrosis * Similar results by Rappaport 1999, Kim et al. 2007, Worsoe et al. 2010, Demel et al., , Demel et al.

42 Overview Meningitis-associated hearing loss in humans Overview of temporal bone anatomy Animal models to study meningitis-associated hearing loss Tools to study hearing in animals (with meningitis) Histomorphologic correlates of meningitis-associated hearing loss Studying Mechanisms of Damage Adjunctive Therapeutic Options of Meningitis-associated Hearing Loss Summary

43 Summary Meningitis-associated hearing loss is the most common long term sequelae Hearing loss in mice closely mimics human course of disease Morphological correlats similar to findings in humans Excellent tool to measure long term effects of e.g. knock outs or therapy Technique is demanding Time consuming experiments Hearing assessment is difficult in the acute stage (anaesthesia in mice)