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Hirose K, Li SZ, Gill R, Hartsock J. Pneumococcal Meningitis Induces Hearing Loss and Cochlear Ossification Modulated by Chemokine Receptors CX3CR1 and CCR2. J Assoc Res Otolaryngol 2024; 25:179-199. [PMID: 38472515 PMCID: PMC11018586 DOI: 10.1007/s10162-024-00935-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Accepted: 01/12/2024] [Indexed: 03/14/2024] Open
Abstract
PURPOSE Pneumococcal meningitis is a major cause of hearing loss and permanent neurological impairment despite widely available antimicrobial therapies to control infection. Methods to improve hearing outcomes for those who survive bacterial meningitis remains elusive. We used a mouse model of pneumococcal meningitis to evaluate the impact of mononuclear phagocytes on hearing outcomes and cochlear ossification by altering the expression of CX3CR1 and CCR2 in these infected mice. METHODS We induced pneumococcal meningitis in approximately 500 C57Bl6 adult mice using live Streptococcus pneumoniae (serotype 3, 1 × 105 colony forming units (cfu) in 10 µl) injected directly into the cisterna magna of anesthetized mice and treated these mice with ceftriaxone daily until recovered. We evaluated hearing thresholds over time, characterized the cochlear inflammatory response, and quantified the amount of new bone formation during meningitis recovery. We used microcomputed tomography (microCT) scans to quantify cochlear volume loss caused by neo-ossification. We also performed perilymph sampling in live mice to assess the integrity of the blood-perilymph barrier during various time intervals after meningitis. We then evaluated the effect of CX3CR1 or CCR2 deletion in meningitis symptoms, hearing loss, macrophage/monocyte recruitment, neo-ossification, and blood labyrinth barrier function. RESULTS Sixty percent of mice with pneumococcal meningitis developed hearing loss. Cochlear fibrosis could be detected within 4 days of infection, and neo-ossification by 14 days. Loss of spiral ganglion neurons was common, and inner ear anatomy was distorted by scarring caused by new soft tissue and bone deposited within the scalae. The blood-perilymph barrier was disrupted at 3 days post infection (DPI) and was restored by seven DPI. Both CCR2 and CX3CR1 monocytes and macrophages were present in the cochlea in large numbers after infection. Neither chemokine receptor was necessary for the induction of hearing loss, cochlear fibrosis, ossification, or disruption of the blood-perilymph barrier. CCR2 knockout (KO) mice suffered the most severe hearing loss. CX3CR1 KO mice demonstrated an intermediate phenotype with greater susceptibility to hearing loss compared to control mice. Elimination of CX3CR1 mononuclear phagocytes during the first 2 weeks after meningitis in CX3CR1-DTR transgenic mice did not protect mice from any of the systemic or hearing sequelae of pneumococcal meningitis. CONCLUSIONS Pneumococcal meningitis can have devastating effects on cochlear structure and function, although not all mice experienced hearing loss or cochlear damage. Meningitis can result in rapid progression of hearing loss with fibrosis starting at four DPI and ossification within 2 weeks of infection detectable by light microscopy. The inflammatory response to bacterial meningitis is robust and can affect all three scalae. Our results suggest that CCR2 may assist in controlling infection and maintaining cochlear patency, as CCR2 knockout mice experienced more severe disease, more rapid hearing loss, and more advanced cochlear ossification after pneumococcal meningitis. CX3CR1 also may play an important role in the maintenance of cochlear patency.
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Affiliation(s)
- Keiko Hirose
- Department of Otolaryngology-Head and Neck Surgery, Washington University School of Medicine, 660 S. Euclid Avenue, Campus Box 8115, St. Louis, MO, 63110, USA.
| | - Song Zhe Li
- Department of Otolaryngology-Head and Neck Surgery, Washington University School of Medicine, 660 S. Euclid Avenue, Campus Box 8115, St. Louis, MO, 63110, USA
| | - Ruth Gill
- Department of Otolaryngology-Head and Neck Surgery, Washington University School of Medicine, 660 S. Euclid Avenue, Campus Box 8115, St. Louis, MO, 63110, USA
- Department of Obstetric and Gynecology, Washington University, St. Louis, MO, USA
| | - Jared Hartsock
- Department of Otolaryngology-Head and Neck Surgery, Washington University School of Medicine, 660 S. Euclid Avenue, Campus Box 8115, St. Louis, MO, 63110, USA
- Turner Scientific, Jacksonville, IL, USA
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2
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Hayashi Y. Signaling pathways regulating the immune function of cochlear supporting cells and their involvement in cochlear pathophysiology. Glia 2024; 72:665-676. [PMID: 37933494 DOI: 10.1002/glia.24476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2022] [Revised: 09/14/2023] [Accepted: 09/20/2023] [Indexed: 11/08/2023]
Abstract
The inner ear, including the cochlea, used to be regarded as an immune-privileged site because of its immunologically isolated environment caused by the blood-labyrinthine barrier. Cochlear resident macrophages, which originate from the yolk sac or fetal liver during the embryonic stage and are maintained after birth, are distributed throughout various regions of the cochlear duct. Intriguingly, these cells are absent in the organ of Corti, where hair cells (HCs) and supporting cells (SCs) are located, except for a limited number of ionized calcium-binding adapter molecule 1 (Iba1)-positive cells. Instead, SCs exert glial functions varying from a quiescent to an emergency state. Notably, SCs acquire the nature of macrophages and begin to secrete inflammatory cytokines during viral infection in the organ of Corti, which is ostensibly unprotected owing to the lack of general resident macrophages. This review provides an overview of both positive and negative functions of SCs enabled to acquire macrophage phenotypes upon viral infection focusing on the signaling pathways that regulate these functions. The former function protects HCs from viral infection by inducting type I interferons, and the latter function induces HC death by necroptosis, leading to sensorineural hearing loss. Thus, SCs play contradictory roles as immune cells with acquired macrophage phenotypes; thereby, they are favorable and unfavorable to HCs, which play a pivotal role in hearing function.
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Affiliation(s)
- Yushi Hayashi
- Department of Molecular and Medical Genetics, Nippon Medical School, Tokyo, Japan
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3
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Le ND, Steinfort M, Grandgirard D, Maleska A, Leppert D, Kuhle J, Leib SL. The CCR5 antagonist maraviroc exerts limited neuroprotection without improving neurofunctional outcome in experimental pneumococcal meningitis. Sci Rep 2022; 12:12945. [PMID: 35902720 PMCID: PMC9334283 DOI: 10.1038/s41598-022-17282-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 07/22/2022] [Indexed: 11/10/2022] Open
Abstract
One-third of pneumococcal meningitis (PM) survivors suffer from neurological sequelae including learning disabilities and hearing loss due to excessive neuroinflammation. There is a lack of efficacious compounds for adjuvant therapy to control this long-term consequence of PM. One hallmark is the recruitment of leukocytes to the brain to combat the bacterial spread. However, this process induces excessive inflammation, causing neuronal injury. Maraviroc (MVC)—a CCR5 antagonist—was demonstrated to inhibit leukocyte recruitment and attenuate neuroinflammation in several inflammatory diseases. Here, we show that in vitro, MVC decreased nitric oxide production in astroglial cells upon pneumococcal stimulation. In vivo, infant Wistar rats were infected with 1 × 104 CFU/ml S. pneumoniae and randomized for treatment with ceftriaxone plus MVC (100 mg/kg) or ceftriaxone monotherapy. During the acute phase, neuroinflammation in the CSF was measured and histopathological analyses were performed to determine neuronal injury. Long-term neurofunctional outcome (learning/memory and hearing capacity) after PM was assessed. MVC treatment reduced hippocampal cell apoptosis but did not affect CSF neuroinflammation and the neurofunctional outcome after PM. We conclude that MVC treatment only exerted limited effect on the pathophysiology of PM and is, therefore, not sufficiently beneficial in this experimental paradigm of PM.
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Affiliation(s)
- Ngoc Dung Le
- Neuroinfection Laboratory, Institute for Infectious Diseases, University of Bern, Bern, Switzerland.,Graduate School for Cellular and Biomedical Sciences (GCB), University of Bern, Bern, Switzerland
| | - Marel Steinfort
- Neuroinfection Laboratory, Institute for Infectious Diseases, University of Bern, Bern, Switzerland
| | - Denis Grandgirard
- Neuroinfection Laboratory, Institute for Infectious Diseases, University of Bern, Bern, Switzerland
| | - Aleksandra Maleska
- Multiple Sclerosis Centre, Neurology, Departments of Head, Spine and Neuromedicine, Biomedicine and Clinical Research, University Hospital Basel and University of Basel, Basel, Switzerland.,Research Center for Clinical Neuroimmunology and Neuroscience (RC2NB), University Hospital and University of Basel, Basel, Switzerland
| | - David Leppert
- Multiple Sclerosis Centre, Neurology, Departments of Head, Spine and Neuromedicine, Biomedicine and Clinical Research, University Hospital Basel and University of Basel, Basel, Switzerland.,Research Center for Clinical Neuroimmunology and Neuroscience (RC2NB), University Hospital and University of Basel, Basel, Switzerland
| | - Jens Kuhle
- Multiple Sclerosis Centre, Neurology, Departments of Head, Spine and Neuromedicine, Biomedicine and Clinical Research, University Hospital Basel and University of Basel, Basel, Switzerland.,Research Center for Clinical Neuroimmunology and Neuroscience (RC2NB), University Hospital and University of Basel, Basel, Switzerland
| | - Stephen L Leib
- Neuroinfection Laboratory, Institute for Infectious Diseases, University of Bern, Bern, Switzerland.
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Triamcinolone acetonide can be detected in cerebrospinal fluid after intratympanic injection. Eur J Pharm Biopharm 2021; 170:52-58. [PMID: 34864199 DOI: 10.1016/j.ejpb.2021.11.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 10/30/2021] [Accepted: 11/28/2021] [Indexed: 11/21/2022]
Abstract
Intratympanically applied treatments are of increasing interest to the otologic community to treat sudden sensorineural hearing loss or vestibular disorders but also to deliver gene therapy agents, or biologics to the inner ear. Further diversion from the middle ear and perilymph to blood circulation and cerebrospinal fluid via the cochlear aqueduct are one of the limiting factors and so far not understood well enough. In this study, intratympanically applied triamcinolone acetonide was determined in cerebrospinal fluid. Additionally, perilymph was sampled through the round window membrane as well as at the lateral semicircular canal to determine drug levels. Of the twenty-one included patients, triamcinolone acetonide was quantifiable in cerebrospinal fluid in 43% at very low levels (range 0 ng/ml - 6.2 ng/ml) which did not correlate with perilymph levels. Drug levels at the two different perilymph sampling sites were within a range of 13.5 ng/ml to 1180.0 ng/ml. Results suggest an equal distribution of triamcinolone acetonide to semicircular canals, which might support the use of triamcinolone acetonide as a treatment option for vestibular pathologies such as Menièrés disease. On the other hand, the distribution to cerebrospinal fluid might be limiting current approaches in gene therapy where a central distribution is unwanted.
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Schon F, Karunakaran A, Shanmuganathan S, Nitkunan A. Orthostatic hearing loss: audiovestibular manifestations of spontaneous intracranial hypotension. Pract Neurol 2020:practneurol-2019-002479. [PMID: 32994365 DOI: 10.1136/practneurol-2019-002479] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/02/2020] [Indexed: 11/03/2022]
Abstract
A 36-year-old woman with severe postural headaches caused by spontaneous intracranial hypotension developed bilateral hearing loss. Her hearing loss varied in severity and also at times affected one ear more than the other. She noticed her hearing returned to normal on lying flat, and this was confirmed on audiometry. Her hearing fully recovered after treatment with blood patches. Audiovestibular symptoms affect up to 70% of people with spontaneous intracranial hypotension but are probably under-reported. Cerebrospinal fluid and inner ear fluids are related in two separate channels: the vestibular and the cochlear aqueducts. We discuss their role in the postural hearing loss of spontaneous intracranial hypotension.
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Affiliation(s)
- Frederick Schon
- Department of Neurology, Croydon University Hospital, Croydon, UK
| | - Arun Karunakaran
- Department of Audiology, Croydon University Hospital, Croydon, UK
| | | | - Arani Nitkunan
- Department of Neurology, Croydon University Hospital, Croydon, UK
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West N, Sass H, Klokker M, Cayé-Thomasen P. Functional Loss After Meningitis-Evaluation of Vestibular Function in Patients With Postmeningitic Hearing Loss. Front Neurol 2020; 11:681. [PMID: 32849181 PMCID: PMC7406674 DOI: 10.3389/fneur.2020.00681] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Accepted: 06/08/2020] [Indexed: 11/13/2022] Open
Abstract
Introduction: The inner ear vestibular system is essential to balance function. Although hearing loss is well-described and quite common following meningitis, the literature evaluating vestibular function following meningitis is very limited. In particular, information on results of contemporary vestibular function tests, e.g., the video head impulse test (VHIT), is scarce. Using contemporary vestibular function tests, this study examines the vestibular function of patients with profound hearing loss (HL) after meningitis. Methods: Review of the literature and retrospective controlled study. Patients: Twenty-one consecutive patients with profound HL after meningitis (cochlear implant candidates) matched with 20 patients with profound HL of unknown etiology and examined during the period 2013-2018. Outcome Measure: Vestibular function loss, as evaluated with VHIT vestibulo-ocular reflex (VOR) gain, eye movement saccades, and cervical vestibular-evoked myogenic potentials (cVEMPs). The results of these tests were correlated to inner ear imaging findings (MRI/CT) and the level of hearing loss. Results: Mean VHIT gain was 0.48 in the meningitis group compared to 0.86 in the control group (p < 0.01). Saccades were present in 21 ears (62%) in the meningitis group compared to six ears (15%) among the controls (p < 0.01). cVEMP responses were present on five ears (18%) in the meningitis group and 25 ears (66%) in the control group (p < 0.01). Discussion: Postmeningitic hearing loss is associated with poor vestibular function, as evaluated by VHIT, saccades, and cVEMP. Loss of vestibular function correlates with the degree of hearing loss and inner ear imaging findings, although not in all cases. Vestibular function should be examined in patients surviving meningitis with hearing loss in order to individualize rehabilitation and improve balance outcome.
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Affiliation(s)
- Niels West
- Department of Otorhinolaryngology Head & Neck Surgery and Audiology, Rigshospitalet, University Hospital of Copenhagen, Copenhagen, Denmark
| | - Hjalte Sass
- Department of Otorhinolaryngology Head & Neck Surgery and Audiology, Rigshospitalet, University Hospital of Copenhagen, Copenhagen, Denmark
| | - Mads Klokker
- Department of Otorhinolaryngology Head & Neck Surgery and Audiology, Rigshospitalet, University Hospital of Copenhagen, Copenhagen, Denmark.,Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Per Cayé-Thomasen
- Department of Otorhinolaryngology Head & Neck Surgery and Audiology, Rigshospitalet, University Hospital of Copenhagen, Copenhagen, Denmark.,Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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Christiansen M, Jensen ES, Brandt CT, Kirchmann M. Otoacoustic emissions in patients with bacterial meningitis. Int J Audiol 2020; 59:647-653. [PMID: 32100579 DOI: 10.1080/14992027.2020.1727967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Objective: Systematic evaluation of studies using otoacoustic emissions (OAEs) to monitor cochlear damage in patients with bacterial meningitis.Design: Systematic review. This includes articles retrieved from PUBMED and EMBASE. The search-strategy was based on the PICO-model. Data processing involved Cochrane Public Health Data Extraction template in addition to assessment of risk of bias and applicability with the Second Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool.Study samples: Thirty-eight articles were identified with 6 studies comprising 391 children and 17 adult patients eligible for full assessment.Results: Studies were heterogenic and the timing of OAE was incomparable between studies. The frequency of severe loss of hearing was reported to occur between 1.6 and 21% of the patients with culture-proven meningitis. The included studies, albeit heterogenic, found OAE-screening feasible and sensitive in children recovering from bacterial meningitis.Conclusion: No children with hearing loss were reported to pass an OAE screening in any of the included studies. The timing, sensitivity and extent of sensorineural hearing loss determined by OAE could not be assessed from the included studies. Levels of risk of bias were inconsistent and the clinical feasibility for routine inclusion of patients with bacterial meningitis was uncertain. The technological development within this field implies the need for further research.
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Affiliation(s)
- Malina Christiansen
- Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark.,Department of Oto-Rhino-Laryngology, Nordsjaellands Hospital, Hillerod, Denmark
| | | | - Christian Thomas Brandt
- Department of Infectious Diseases, Nordsjaellands Hospital, Copenhagen Denmark.,Department of Clinical Medicine, Zealand University Hospital, University of Copenhagen
| | - Malene Kirchmann
- Department of Oto-Rhino-Laryngology, Nordsjaellands Hospital, Hillerod, Denmark
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8
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Muri L, Le ND, Zemp J, Grandgirard D, Leib SL. Metformin mediates neuroprotection and attenuates hearing loss in experimental pneumococcal meningitis. J Neuroinflammation 2019; 16:156. [PMID: 31351490 PMCID: PMC6660697 DOI: 10.1186/s12974-019-1549-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Accepted: 07/18/2019] [Indexed: 12/16/2022] Open
Abstract
Background Pneumococcal meningitis is associated with high risk of neurological sequelae such as cognitive impairment and hearing loss. These sequelae are due to parenchymal brain and inner ear damage primarily induced by the excessive inflammatory reaction in response to bacterial brain invasion. Metformin—a biguanide drug to treat diabetes mellitus type 2—was recently found to suppress neuroinflammation and induce neuroregeneration. This study evaluated the effect of metformin adjunctive to antibiotics on neuroinflammation, brain and inner ear damage, and neurofunctional outcome in experimental pediatric pneumococcal meningitis. Methods Eleven-day-old Wistar rats were infected intracisternally with 5.22 ± 1.27 × 103 CFU Streptococcus pneumoniae and randomized for treatment with metformin (50 mg/kg, i.p., once daily for 3 weeks) plus ceftriaxone (100 mg/kg, i.p., bid, n = 61) or ceftriaxone monotherapy (n = 79). Cortical damage and hippocampal apoptosis were evaluated histomorphometrically 42 h post infection. Cerebrospinal fluid cytokine levels were analyzed during acute infection. Five weeks post infection, auditory brainstem responses were measured to determine hearing thresholds. Spiral ganglion neuron density and abundance of recently proliferated and integrated hippocampal granule neurons were assessed histologically. Additionally, the anti-inflammatory effect of metformin was studied in primary rat astroglial cells in vitro. Results Upon pneumococcal infection, metformin treatment significantly reduced levels of inflammatory cytokines and nitric oxide production in cerebrospinal fluid and in astroglial cell cultures in vitro (p < 0.05). Compared to animals receiving ceftriaxone monotherapy, adjunctive metformin significantly reduced cortical necrosis (p < 0.02) during acute infection and improved median click-induced hearing thresholds (60 dB vs. 100 dB, p < 0.002) 5 weeks after infection. Adjuvant metformin significantly improved pure tone hearing thresholds at all assessed frequencies compared to ceftriaxone monotherapy (p < 0.05) and protected from PM-induced spiral ganglion neuron loss in the inner ear (p < 0.05). Conclusion Adjuvant metformin reduces brain injury during pneumococcal meningitis by decreasing the excessive neuroinflammatory response. Furthermore, it protects spiral ganglion neurons in the inner ear and improves hearing impairments after experimental pneumococcal meningitis. These results identify adjuvant metformin as a promising therapeutic option to improve the outcome after pediatric pneumococcal meningitis. Electronic supplementary material The online version of this article (10.1186/s12974-019-1549-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Lukas Muri
- Neuroinfection Laboratory, Institute for Infectious Diseases, University of Bern, Friedbühlstrasse 51, 3010, Bern, Switzerland.,Graduate School for Cellular and Biomedical Sciences (GCB), University of Bern, Mittelstrasse 43, 3012, Bern, Switzerland
| | - Ngoc Dung Le
- Neuroinfection Laboratory, Institute for Infectious Diseases, University of Bern, Friedbühlstrasse 51, 3010, Bern, Switzerland.,Graduate School for Cellular and Biomedical Sciences (GCB), University of Bern, Mittelstrasse 43, 3012, Bern, Switzerland
| | - Jonas Zemp
- Neuroinfection Laboratory, Institute for Infectious Diseases, University of Bern, Friedbühlstrasse 51, 3010, Bern, Switzerland
| | - Denis Grandgirard
- Neuroinfection Laboratory, Institute for Infectious Diseases, University of Bern, Friedbühlstrasse 51, 3010, Bern, Switzerland
| | - Stephen L Leib
- Neuroinfection Laboratory, Institute for Infectious Diseases, University of Bern, Friedbühlstrasse 51, 3010, Bern, Switzerland.
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Erni ST, Fernandes G, Buri M, Perny M, Rutten RJ, van Noort JM, Senn P, Grandgirard D, Roccio M, Leib SL. Anti-inflammatory and Oto-Protective Effect of the Small Heat Shock Protein Alpha B-Crystallin (HspB5) in Experimental Pneumococcal Meningitis. Front Neurol 2019; 10:570. [PMID: 31244750 PMCID: PMC6573805 DOI: 10.3389/fneur.2019.00570] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Accepted: 05/15/2019] [Indexed: 12/18/2022] Open
Abstract
Sensorineural hearing loss is the most common long-term deficit after pneumococcal meningitis (PM), occurring in up to 30% of surviving patients. The infection and the following overshooting inflammatory host response damage the vulnerable sensory cells of the inner ear, resulting in loss of hair cells and spiral ganglion neurons, ultimately leading to elevated hearing thresholds. Here, we tested the oto-protective properties of the small heat shock protein alpha B-crystallin (HspB5) with previously reported anti-inflammatory, anti-apoptotic and neuroprotective functions, in an experimental model of PM-induced hearing loss. We analyzed the effect of local and systemic delivery of HspB5 in an infant rat model of PM, as well as ex vivo, using whole mount cultures. Cytokine secretion profile, hearing thresholds and inner ear damage were assessed at predefined stages of the disease up to 1 month after infection. PM was accompanied by elevated pro-inflammatory cytokine concentrations in the cerebrospinal fluid (CSF), leukocyte and neutrophil infiltration in the perilymphatic spaces of the cochlea with neutrophils extracellular trap formation during the acute phase of the disease. Elevated hearing thresholds were measured after recovery from meningitis. Intracisternal but not intraperitoneal administration of HspB5 significantly reduced the levels of TNF-α, IL-6 IFN-γ and IL-10 in the acute phase of the disease. This resulted in a greater outer hair cell survival, as well as improved hearing thresholds at later stages. These results suggest that high local concentrations of HspB5 are needed to prevent inner ear damage in acute PM. HspB5 represents a promising therapeutic option to improve the auditory outcome and counteract hearing loss after PM.
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Affiliation(s)
- Silvia T Erni
- Neuroinfection Laboratory, Institute for Infectious Diseases, University of Bern, Bern, Switzerland.,Cluster for Regenerative Neuroscience, DBMR, University of Bern, Bern, Switzerland.,Laboratory of Inner Ear Research, DBMR, University of Bern, Bern, Switzerland.,Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - Gabriella Fernandes
- Neuroinfection Laboratory, Institute for Infectious Diseases, University of Bern, Bern, Switzerland.,Cluster for Regenerative Neuroscience, DBMR, University of Bern, Bern, Switzerland.,Laboratory of Inner Ear Research, DBMR, University of Bern, Bern, Switzerland
| | - Michelle Buri
- Neuroinfection Laboratory, Institute for Infectious Diseases, University of Bern, Bern, Switzerland.,Cluster for Regenerative Neuroscience, DBMR, University of Bern, Bern, Switzerland
| | - Michael Perny
- Neuroinfection Laboratory, Institute for Infectious Diseases, University of Bern, Bern, Switzerland.,Cluster for Regenerative Neuroscience, DBMR, University of Bern, Bern, Switzerland.,Laboratory of Inner Ear Research, DBMR, University of Bern, Bern, Switzerland
| | | | | | - Pascal Senn
- Service d'oto-rhino-laryngologie (ORL) et de chirurgie cervico-faciale, Département des Neurosciences Cliniques, Hôpitaux Universitaires de Genève, Geneva, Switzerland
| | - Denis Grandgirard
- Neuroinfection Laboratory, Institute for Infectious Diseases, University of Bern, Bern, Switzerland.,Cluster for Regenerative Neuroscience, DBMR, University of Bern, Bern, Switzerland
| | - Marta Roccio
- Cluster for Regenerative Neuroscience, DBMR, University of Bern, Bern, Switzerland.,Laboratory of Inner Ear Research, DBMR, University of Bern, Bern, Switzerland.,Department of Otorhinolaryngology, Head & Neck Surgery, Inselspital, Bern, Switzerland
| | - Stephen L Leib
- Neuroinfection Laboratory, Institute for Infectious Diseases, University of Bern, Bern, Switzerland.,Cluster for Regenerative Neuroscience, DBMR, University of Bern, Bern, Switzerland
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Muri L, Grandgirard D, Buri M, Perny M, Leib SL. Combined effect of non-bacteriolytic antibiotic and inhibition of matrix metalloproteinases prevents brain injury and preserves learning, memory and hearing function in experimental paediatric pneumococcal meningitis. J Neuroinflammation 2018; 15:233. [PMID: 30131074 PMCID: PMC6103863 DOI: 10.1186/s12974-018-1272-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Accepted: 08/08/2018] [Indexed: 12/04/2022] Open
Abstract
BACKGROUND Pneumococcal meningitis is associated with high mortality and morbidity rates. Up to 50% of survivors show neurologic sequelae including hearing loss, cognitive impairments and learning disabilities, being particularly detrimental in affected infants and children where adjuvant therapy with dexamethasone has no proven beneficial effect. We evaluated the effect of concomitantly targeting specific pathophysiological mechanisms responsible for brain damage-i.e. matrix-metalloproteinase (MMP) activity and the exacerbated cerebral inflammation provoked through antibiotic-induced bacterial lysis. Here, we combined adjunctive therapies previously shown to be neuroprotective when used as single adjuvant therapies. METHODS Eleven-day-old Wistar rats were infected intracisternally with 6.44 ± 2.17 × 103 CFU Streptococcus pneumoniae and randomised for treatment with ceftriaxone combined with (a) single adjuvant therapy with daptomycin (n = 24), (b) single adjuvant therapy with Trocade (n = 24), (c) combined adjuvant therapy (n = 66) consisting of daptomycin and Trocade, or (d) ceftriaxone monotherapy (n = 42). Clinical parameters and inflammatory CSF cytokine levels were determined during acute meningitis. Cortical damage and hippocampal apoptosis were assessed 42 h after infection. Morris water maze and auditory brainstem responses were used to assess neurofunctional outcome 3 weeks after infection. RESULTS We found significantly reduced apoptosis in the hippocampal subgranular zone in infant rats receiving adjuvant Trocade (p < 0.01) or combined adjuvant therapy (p < 0.001). Cortical necrosis was significantly reduced in rats treated with adjuvant daptomycin (p < 0.05) or combined adjuvant therapy (p < 0.05) compared to ceftriaxone monotherapy. Six hours after treatment initiation, CSF cytokine levels were significantly reduced for TNF-α (p < 0.01), IL-1β (p < 0.01), IL-6 (p < 0.001) and IL-10 (p < 0.01) in animals receiving combined adjuvant intervention compared to ceftriaxone monotherapy. Importantly, combined adjuvant therapy significantly improved learning and memory performance in infected animals and reduced hearing loss (77.14 dB vs 60.92 dB, p < 0.05) by preserving low frequency hearing capacity, compared to ceftriaxone monotherapy. CONCLUSION Combined adjuvant therapy with the non-bacteriolytic antibiotic daptomycin and the MMP inhibitor Trocade integrates the neuroprotective effects of both single adjuvants in experimental paediatric pneumococcal meningitis by reducing neuroinflammation and brain damage, thereby improving neurofunctional outcome. This strategy represents a promising therapeutic option to improve the outcome of paediatric patients suffering from pneumococcal meningitis.
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Affiliation(s)
- Lukas Muri
- Neuroinfection Laboratory, Institute for Infectious Diseases, University of Bern, Friedbühlstrasse 51, 3001 Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences (GCB), University of Bern, Freiestrasse 1, 3012 Bern, Switzerland
| | - Denis Grandgirard
- Neuroinfection Laboratory, Institute for Infectious Diseases, University of Bern, Friedbühlstrasse 51, 3001 Bern, Switzerland
| | - Michelle Buri
- Neuroinfection Laboratory, Institute for Infectious Diseases, University of Bern, Friedbühlstrasse 51, 3001 Bern, Switzerland
| | - Michael Perny
- Neuroinfection Laboratory, Institute for Infectious Diseases, University of Bern, Friedbühlstrasse 51, 3001 Bern, Switzerland
| | - Stephen L. Leib
- Neuroinfection Laboratory, Institute for Infectious Diseases, University of Bern, Friedbühlstrasse 51, 3001 Bern, Switzerland
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The Severity of Infection Determines the Localization of Damage and Extent of Sensorineural Hearing Loss in Experimental Pneumococcal Meningitis. J Neurosci 2017; 36:7740-9. [PMID: 27445150 DOI: 10.1523/jneurosci.0554-16.2016] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Accepted: 06/09/2016] [Indexed: 12/20/2022] Open
Abstract
UNLABELLED Hearing loss is an important sequela of pneumococcal meningitis (PM), occurring in up to 30% of survivors. The role of the severity of infection on hearing function and pathomorphological consequences in the cochlea secondary to PM have not been investigated to date. Using a well-established model of PM, we systematically investigated the functional hearing outcome and the long-term fate of neurosensory cells in the cochlea, i.e., hair cells and spiral ganglion neurons (SGNs), with a focus on their tonotopic distribution. Intracisternal infection of infant rats with increasing inocula of Streptococcus pneumoniae resulted in a dose-dependent increase in CSF levels of interleukin-1β, interleukin-6, tumor necrosis factor α, interleukin-10, and interferon-γ in acute disease. The severity of long-term hearing loss at 3 weeks after infection, measured by auditory brainstem response recordings, correlated to the initial inoculum dose and to the levels of proinflammatory cytokines determined in the acute phase of PM. Quantitative cochlear histomorphology revealed a significant loss of SGNs and outer hair cells that strongly correlated to the level of infection, with the most severe damage occurring in the basal part of the cochlea. Inner hair cells (IHCs) were not significantly affected throughout the entire cochlea. However, surviving IHCs lost synaptic connectivity to remaining SGNs in all cochlear regions. These findings provide evidence that the inoculum concentration, i.e., severity of infection, is the major determinant of long-term morphological cell pathologies in the cochlea and functional hearing loss. SIGNIFICANCE STATEMENT Hearing loss is a neurofunctional deficit occurring in up to 30% of patients surviving pneumococcal meningitis (PM). Here, we analyze the correlation between the severity of infection and the inflammatory response in the CSF, the tonotopic distribution of neurosensory pathologies in the cochlea, and the long-term hearing function in a rat model of pneumococcal meningitis. Our study identifies the severity of infection as the key determinant of long-term hearing loss, underlining the importance of the prompt institution of antibiotic therapy in patients suffering from PM. Furthermore, our findings reveal in detail the spatial loss of cochlear neurosensory cells, providing new insights into the pathogenesis of meningitis-associated hearing loss that reveal new starting points for the development of otoprotective therapies.
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Perny M, Solyga M, Grandgirard D, Roccio M, Leib SL, Senn P. Streptococcus pneumoniae-induced ototoxicity in organ of Corti explant cultures. Hear Res 2017; 350:100-109. [PMID: 28460251 DOI: 10.1016/j.heares.2017.04.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 04/11/2017] [Accepted: 04/23/2017] [Indexed: 12/20/2022]
Abstract
Hearing loss remains the most common long-term complication of pneumococcal meningitis (PM) reported in up to 30% of survivors. Streptococcus pneumoniae have been shown to possess different ototoxic properties. Here we present a novel ex vivo experimental setup to examine in detail the pattern of hair cell loss upon exposure to different S. pneumoniae strains, therefore recapitulating pathogen derived aspects of PM-induced hearing loss. Our results show a higher susceptibility towards S. pneumoniae-induced cochlear damage for outer hair cells (OHC) compared to inner hair cells (IHC), which is consistent with in vivo data. S. pneumoniae-induced hair cell loss was both time and dose-dependent. Moreover, we have found significant differences in the level of cell damage between tissue from the basal and the apical turns. This shows that the higher vulnerability of hair cells located at high frequency regions observed in vivo cannot be explained solely by the spatial organisation and bacterial infiltration from the basal portion of the cochlea. Using a wild type D39 strain and a mutant defective for the pneumolysin (PLY) gene, we also have shown that the toxin PLY is an important factor involved in ototoxic damages. The obtained results indicate that PLY can cause both IHC and OHC loss. Finally, we are reporting here for the first time a higher vulnerability of HC located at the basal and middle cochlear region to pneumolysin-induced damage. The detailed description of the susceptibility of hair cells to Streptococcus pneumoniae provided in this report can in the future determine the choice and the development of novel otoprotective therapies during pneumococcal meningitis.
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Affiliation(s)
- Michael Perny
- Neuroinfection Laboratory, Institute for Infectious Diseases, University of Bern, Switzerland; Inner Ear Research Laboratory, Department of Otorhinolaryngology, Head& Neck Surgery, Inselspital Bern and Department of Clinical Research, University of Bern, Switzerland; Cluster for Regenerative Neuroscience, Department of Clinical Research, University of Bern, Switzerland
| | - Magdalena Solyga
- Inner Ear Research Laboratory, Department of Otorhinolaryngology, Head& Neck Surgery, Inselspital Bern and Department of Clinical Research, University of Bern, Switzerland; Cluster for Regenerative Neuroscience, Department of Clinical Research, University of Bern, Switzerland
| | - Denis Grandgirard
- Neuroinfection Laboratory, Institute for Infectious Diseases, University of Bern, Switzerland; Cluster for Regenerative Neuroscience, Department of Clinical Research, University of Bern, Switzerland
| | - Marta Roccio
- Inner Ear Research Laboratory, Department of Otorhinolaryngology, Head& Neck Surgery, Inselspital Bern and Department of Clinical Research, University of Bern, Switzerland; Cluster for Regenerative Neuroscience, Department of Clinical Research, University of Bern, Switzerland
| | - Stephen L Leib
- Neuroinfection Laboratory, Institute for Infectious Diseases, University of Bern, Switzerland; Cluster for Regenerative Neuroscience, Department of Clinical Research, University of Bern, Switzerland.
| | - Pascal Senn
- Inner Ear Research Laboratory, Department of Otorhinolaryngology, Head& Neck Surgery, Inselspital Bern and Department of Clinical Research, University of Bern, Switzerland; Department of Otorhinolaryngology, Head & Neck Surgery, University Hospital Geneva (HUG), Genève, Switzerland; Cluster for Regenerative Neuroscience, Department of Clinical Research, University of Bern, Switzerland.
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Møller MN, Kirkeby S, Cayé-Thomasen P. Innate immune defense in the inner ear - mucines are expressed by the human endolymphatic sac. J Anat 2016; 230:297-302. [PMID: 28106268 DOI: 10.1111/joa.12559] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/05/2016] [Indexed: 01/31/2023] Open
Abstract
The human endolymphatic sac has been shown recently to have immunological capacities and has thus been proposed as the main entity protecting the inner ear from pathogen invasion, equivalent to mucosa-associated lymphoid tissue (MALT). Although the sac expresses molecules of the innate immune system, the potential expression of members of the important mucin family has not been detailed. Thus, this paper explores endolymphatic sac expression of a number of mucins and mucin precursors. Twelve fresh tissue samples from the human endolymphatic sac were obtained during translabyrinthine surgery. The expression of Mucin 1, 2, 5B/AC and 16, as well as the core structure elements (mucin precursors) T-antigen, Tn-antigen and Sialyl-Tn-antigen was investigated by immunohistochemistry. The endolymphatic sac epithelium expressed MUC1 (both apically towards the endolymphatic sac (ES) lumen and basally towards the capillary network), MUC 16 and Tn-antigen. There was no labeling after incubation with antibodies against T-antigen, sialyl-Tn-antigen, MUC2 and MUC5B/AC. We conclude that the human endolymphatic sac epithelium expresses a number of mucin molecules, which supports the hypothesis of the sac as the primary immunological tissue structure of the inner ear, equivalent to MALT in other organs. The mucins may also play a role in the formation and continuous homeostasis of the inner ear fluids, as well as the pathogenesis of Meniere's disease.
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Affiliation(s)
- Martin N Møller
- Department of Otorhinolaryngology, Head and Neck Surgery, Rigshospitalet, Faculty of Medical and Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Svend Kirkeby
- Department of Oral Medicine, Dental School, Panum Institute, Faculty of Medical and Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Per Cayé-Thomasen
- Department of Otorhinolaryngology, Head and Neck Surgery, Rigshospitalet, Faculty of Medical and Health Sciences, University of Copenhagen, Copenhagen, Denmark
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Møller MN, Kirkeby S, Vikeså J, Nielsen FC, Cayé-Thomasen P. Gene expression demonstrates an immunological capacity of the human endolymphatic sac. Laryngoscope 2015; 125:E269-75. [DOI: 10.1002/lary.25242] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/20/2015] [Indexed: 11/06/2022]
Affiliation(s)
- Martin Nue Møller
- Department of Otorhinolaryngology; Head and Neck Surgery, Rigshospitalet (m.n.m., p.c-t.)
| | - Svend Kirkeby
- Department of Oral Medicine; Dental School; Panum Institute (s.k.); University of Copenhagen
| | - Jonas Vikeså
- Center for Genomic Medicine (j,v., f.c.n.); University of Copenhagen, Rigshospitalet
| | - Finn Cilius Nielsen
- Center for Genomic Medicine (j,v., f.c.n.); University of Copenhagen, Rigshospitalet
| | - Per Cayé-Thomasen
- Department of Otorhinolaryngology; Head and Neck Surgery, Rigshospitalet (m.n.m., p.c-t.)
- The Faculty of Health and Medical Sciences (p.c-t.); University of Copenhagen; Copenhagen Denmark
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Møller MN, Brandt C, Østergaard C, Caye-Thomasen P. Endolymphatic sac involvement in bacterial meningitis. Eur Arch Otorhinolaryngol 2014; 272:843-851. [DOI: 10.1007/s00405-014-2884-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2013] [Accepted: 01/03/2014] [Indexed: 11/24/2022]
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