1
|
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.
Collapse
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
| |
Collapse
|
2
|
Lee MP, Waldhaus J. In vitro and in vivo models: What have we learnt about inner ear regeneration and treatment for hearing loss? Mol Cell Neurosci 2022; 120:103736. [PMID: 35577314 PMCID: PMC9551661 DOI: 10.1016/j.mcn.2022.103736] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 04/29/2022] [Accepted: 05/10/2022] [Indexed: 01/07/2023] Open
Abstract
The sensory cells of the inner ear, called hair cells, do not regenerate spontaneously and therefore, hair cell loss and subsequent hearing loss are permanent in humans. Conversely, functional hair cell regeneration can be observed in non-mammalian vertebrate species like birds and fish. Also, during postnatal development in mice, limited regenerative capacity and the potential to isolate stem cells were reported. Together, these findings spurred the interest of current research aiming to investigate the endogenous regenerative potential in mammals. In this review, we summarize current in vitro based approaches and briefly introduce different in vivo model organisms utilized to study hair cell regeneration. Furthermore, we present an overview of the findings that were made synergistically using both, the in vitro and in vivo based tools.
Collapse
Affiliation(s)
- Mary P Lee
- Department of Otolaryngology-Head and Neck Surgery, Kresge Hearing Research Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Joerg Waldhaus
- Department of Otolaryngology-Head and Neck Surgery, Kresge Hearing Research Institute, University of Michigan, Ann Arbor, MI 48109, USA.
| |
Collapse
|
3
|
Erni ST, Gill JC, Palaferri C, Fernandes G, Buri M, Lazarides K, Grandgirard D, Edge ASB, Leib SL, Roccio M. Hair Cell Generation in Cochlear Culture Models Mediated by Novel γ-Secretase Inhibitors. Front Cell Dev Biol 2021; 9:710159. [PMID: 34485296 PMCID: PMC8414802 DOI: 10.3389/fcell.2021.710159] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2021] [Accepted: 07/26/2021] [Indexed: 12/30/2022] Open
Abstract
Sensorineural hearing loss is prevalent within society affecting the quality of life of 460 million worldwide. In the majority of cases, this is due to insult or degeneration of mechanosensory hair cells in the cochlea. In adult mammals, hair cell loss is irreversible as sensory cells are not replaced spontaneously. Genetic inhibition of Notch signaling had been shown to induce hair cell formation by transdifferentiation of supporting cells in young postnatal rodents and provided an impetus for targeting Notch pathway with small molecule inhibitors for hearing restoration. Here, the oto-regenerative potential of different γ-secretase inhibitors (GSIs) was evaluated in complementary assay models, including cell lines, organotypic cultures of the organ of Corti and cochlear organoids to characterize two novel GSIs (CPD3 and CPD8). GSI-treatment induced hair cell gene expression in all these models and was effective in increasing hair cell numbers, in particular outer hair cells, both in baseline conditions and in response to ototoxic damage. Hair cells were generated from transdifferentiation of supporting cells. Similar findings were obtained in cochlear organoid cultures, used for the first time to probe regeneration following sisomicin-induced damage. Finally, effective absorption of a novel GSI through the round window membrane and hair cell induction was attained in a whole cochlea culture model and in vivo pharmacokinetic comparisons of transtympanic delivery of GSIs and different vehicle formulations were successfully conducted in guinea pigs. This preclinical evaluation of targeting Notch signaling with novel GSIs illustrates methods of characterization for hearing restoration molecules, enabling translation to more complex animal studies and clinical research.
Collapse
Affiliation(s)
- Silvia T Erni
- Neuroinfection Laboratory, Institute for Infectious Diseases, University of Bern, Bern, Switzerland.,Cluster for Regenerative Neuroscience, Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland.,Laboratory of Inner Ear Research, Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland.,Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - John C Gill
- Audion Therapeutics B.V., Amsterdam, Netherlands
| | - Carlotta Palaferri
- Neuroinfection Laboratory, Institute for Infectious Diseases, University of Bern, Bern, Switzerland.,Cluster for Regenerative Neuroscience, Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland.,Laboratory of Inner Ear Research, Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland
| | - Gabriella Fernandes
- Neuroinfection Laboratory, Institute for Infectious Diseases, University of Bern, Bern, Switzerland.,Cluster for Regenerative Neuroscience, Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland.,Laboratory of Inner Ear Research, Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland
| | - Michelle Buri
- Neuroinfection Laboratory, Institute for Infectious Diseases, University of Bern, Bern, Switzerland.,Cluster for Regenerative Neuroscience, Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland.,Laboratory of Inner Ear Research, Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland
| | | | - Denis Grandgirard
- Neuroinfection Laboratory, Institute for Infectious Diseases, University of Bern, Bern, Switzerland.,Cluster for Regenerative Neuroscience, Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland
| | - Albert S B Edge
- Massachusetts Eye and Ear, Boston, MA, United States.,Harvard Medical School, Boston, MA, United States.,Harvard Stem Cell Institute, Cambridge, MA, United States
| | - Stephen L Leib
- Neuroinfection Laboratory, Institute for Infectious Diseases, University of Bern, Bern, Switzerland.,Cluster for Regenerative Neuroscience, Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland
| | - Marta Roccio
- Cluster for Regenerative Neuroscience, Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland.,Laboratory of Inner Ear Research, Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland.,Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital Zurich, Zurich, Switzerland.,Department of Otorhinolaryngology, University of Zurich, Zurich, Switzerland
| |
Collapse
|
4
|
Cortex Cercis chinensis Granules Attenuate Streptococcus pneumoniae Virulence by Targeting Pneumolysin. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2020; 2020:8537026. [PMID: 32617112 PMCID: PMC7315261 DOI: 10.1155/2020/8537026] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 05/03/2020] [Accepted: 05/12/2020] [Indexed: 11/17/2022]
Abstract
Pore-forming toxins produced by bacteria are some of the most important molecular weapons for bacterial virulence. Pneumolysin (PLY) is a pore-forming toxin secreted by Streptococcus pneumoniae (S. pneumoniae) and plays a vital role in the spread, colonization, and invasion of this bacterium in the host, indicating that PLY is a promising target for developing treatments against S. pneumoniae infection. In this study, Cortex Cercis chinensis granules (CCCGs), a prescription drug on the market, were shown to inhibit the pore-forming activity of PLY and protect against PLY-mediated cell hemolysis and A549 cell death without antibacterial activity or inhibition of PLY production. In addition, CCCG treatment inhibited the oligomerization of PLY. Animal experiments showed that CCCGs can reduce the death of mice infected with S. pneumoniae, the degree of pathological damage to the lungs, and the levels of TNF-α and IL-6 in the lungs. In summary, our results demonstrated that CCCGs, a marketed Chinese medicine, inhibit PLY activity and subsequently attenuate S. pneumoniae virulence, which would offer a novel strategy for fighting S. pneumoniae infection and a new use for CCCGs.
Collapse
|
5
|
Basta D, Gröschel M, Strübing I, Boyle P, Fröhlich F, Ernst A, Seidl R. Near-infrared-light pre-treatment attenuates noise-induced hearing loss in mice. PeerJ 2020; 8:e9384. [PMID: 32596055 PMCID: PMC7305775 DOI: 10.7717/peerj.9384] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Accepted: 05/28/2020] [Indexed: 12/02/2022] Open
Abstract
Noise induced hearing loss (NIHL) is accompanied by a reduction of cochlear hair cells and spiral ganglion neurons. Different approaches have been applied to prevent noise induced apoptosis / necrosis. Physical intervention is one technique currently under investigation. Specific wavelengths within the near-infrared light (NIR)-spectrum are known to influence cytochrome-c-oxidase activity, which leads in turn to a decrease in apoptotic mechanisms. It has been shown recently that NIR can significantly decrease the cochlear hair cell loss if applied daily for 12 days after a noise exposure. However, it is still unclear if a single NIR-treatment, just before a noise exposure, could induce similar protective effects. Therefore, the present study was conducted to investigate the effect of a single NIR-pre-treatment aimed at preventing or limiting NIHL. The cochleae of adult NMRI-mice were pre-treated with NIR-light (808 nm, 120 mW) for 5, 10, 20, 30 or 40 minutes via the external ear canal. All animals were noised exposed immediately after the pre-treatment by broad band noise (5–20 kHz) for 30 minutes at 115 dB SPL. Frequency specific ABR-recordings to determine auditory threshold shift were carried out before the pre-treatment and two weeks after the noise exposure. The amplitude increase for wave IV and cochlear hair cell loss were determined. A further group of similar mice was noise exposed only and served as a control for the NIR pre-exposed groups. Two weeks after noise exposure, the ABR threshold shifts of NIR-treated animals were significantly lower (p < 0.05) than those of the control animals. The significance was at three frequencies for the 5-minute pre-treatment group and across the entire frequency range for all other treatment groups. Due to NIR light, the amplitude of wave four deteriorates significantly less after noise exposure than in controls. The NIR pre-treatment had no effect on the loss of outer hair cells, which was just as high with or without NIR-light pre-exposure. Relative to the entire number of outer hair cells across the whole cochlea, outer hair cell loss was rather negligible. No inner hair cell loss whatever was detected. Our results suggest that a single NIR pre-treatment induces a very effective protection of cochlear structures from noise exposure. Pre-exposure of 10 min seems to emerge as the optimal dosage for our experimental setup. A saturated effect occurred with higher dosage-treatments. These results are relevant for protection of residual hearing in otoneurosurgery such as cochlear implantation.
Collapse
Affiliation(s)
- Dietmar Basta
- Department of ENT at ukb, Charité Medical School, University of Berlin, Berlin, Germany
| | - Moritz Gröschel
- Department of ENT at ukb, Charité Medical School, University of Berlin, Berlin, Germany
| | - Ira Strübing
- Department of ENT at ukb, Charité Medical School, University of Berlin, Berlin, Germany
| | | | - Felix Fröhlich
- Department of ENT at ukb, Charité Medical School, University of Berlin, Berlin, Germany
| | - Arne Ernst
- Department of ENT at ukb, Charité Medical School, University of Berlin, Berlin, Germany
| | - Rainer Seidl
- Department of ENT at ukb, Charité Medical School, University of Berlin, Berlin, Germany
| |
Collapse
|
6
|
Muri L, Leppert D, Grandgirard D, Leib SL. MMPs and ADAMs in neurological infectious diseases and multiple sclerosis. Cell Mol Life Sci 2019; 76:3097-3116. [PMID: 31172218 PMCID: PMC7079810 DOI: 10.1007/s00018-019-03174-6] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 05/23/2019] [Accepted: 05/29/2019] [Indexed: 12/24/2022]
Abstract
Metalloproteinases-such as matrix metalloproteinases (MMPs) and a disintegrin and metalloproteinases (ADAMs)-are involved in various diseases of the nervous system but also contribute to nervous system development, synaptic plasticity and neuroregeneration upon injury. MMPs and ADAMs proteolytically cleave many substrates including extracellular matrix components but also signaling molecules and receptors. During neuroinfectious disease with associated neuroinflammation, MMPs and ADAMs regulate blood-brain barrier breakdown, bacterial invasion, neutrophil infiltration and cytokine signaling. Specific and broad-spectrum inhibitors for MMPs and ADAMs have experimentally been shown to decrease neuroinflammation and brain damage in diseases with excessive neuroinflammation as a common denominator, such as pneumococcal meningitis and multiple sclerosis, thereby improving the disease outcome. Timing of metalloproteinase inhibition appears to be critical to effectively target the cascade of pathophysiological processes leading to brain damage without inhibiting the neuroregenerative effects of metalloproteinases. As the critical role of metalloproteinases in neuronal repair mechanisms and regeneration was only lately recognized, the original idea of chronic MMP inhibition needs to be conceptually revised. Recently accumulated research urges for a second chance of metalloproteinase inhibitors, which-when correctly applied and dosed-harbor the potential to improve the outcome of different neuroinflammatory diseases.
Collapse
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
| | - David Leppert
- Department of Neurology, University Hospital Basel, Petersgraben 4, 4031, Basel, Switzerland
| | - Denis Grandgirard
- 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.
| |
Collapse
|
7
|
Combining Ceftriaxone with Doxycycline and Daptomycin Reduces Mortality, Neuroinflammation, Brain Damage, and Hearing Loss in Infant Rat Pneumococcal Meningitis. Antimicrob Agents Chemother 2019; 63:AAC.00220-19. [PMID: 31061158 DOI: 10.1128/aac.00220-19] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 04/30/2019] [Indexed: 02/07/2023] Open
Abstract
Despite appropriate antibiotic therapy, pneumococcal meningitis (PM) is associated with a case fatality rate of up to 30% in high-income countries. Survivors often suffer from severe lifelong disabilities. An excessive inflammatory reaction drives the pathophysiology, leading to brain damage and neurologic sequelae. We aimed to improve the outcome of experimental PM by simultaneously targeting different pathophysiological mechanisms with combined adjunctive therapies previously shown to be neuroprotective. In vitro, the anti-inflammatory effects of doxycycline and daptomycin were evaluated on primary rat astroglial cells stimulated with Streptococcus pneumoniae Eleven-day-old infant Wistar rats were infected intracisternally with S. pneumoniae and randomized for treatment with ceftriaxone or combination adjuvant therapy consisting of ceftriaxone, daptomycin, and doxycycline. During acute PM, combined-adjuvant therapy with ceftriaxone, daptomycin, and doxycycline increased the survival rate from 64.1% to 85.8% (P < 0.01) and alleviated weight loss compared to ceftriaxone monotherapy (P < 0.01). Levels of inflammatory cytokines were significantly reduced by combined-adjuvant therapy in vitro (P < 0.0001) and in cerebrospinal fluid in vivo (P < 0.05). In infected animals treated with combined adjunctive therapy, cortical damage was significantly reduced (P < 0.05), and animals showed a trend toward better hearing capacity 3 weeks after the infection (P = 0.089), an effect which was significant in mildly infected animals (48 decibels [dB] versus 67.22 dB; P < 0.05). These mildly infected animals showed significantly reduced cochlear fibrous occlusion (P < 0.01). By combining nonbacteriolytic daptomycin and anti-inflammatory doxycycline with ceftriaxone, the previously reported beneficial effects of the drugs were cumulated and identified the triple-antibiotic therapy as a promising therapeutic option for pediatric PM.
Collapse
|
8
|
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.
Collapse
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
| |
Collapse
|
9
|
Ogier JM, Burt RA, Drury HR, Lim R, Nayagam BA. Organotypic Culture of Neonatal Murine Inner Ear Explants. Front Cell Neurosci 2019; 13:170. [PMID: 31130846 PMCID: PMC6509234 DOI: 10.3389/fncel.2019.00170] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2018] [Accepted: 04/11/2019] [Indexed: 01/08/2023] Open
Abstract
The inner ear is a complex organ containing highly specialised cell types and structures that are critical for sensing sound and movement. In vivo, the inner ear is difficult to study due to the osseous nature of the otic capsule and its encapsulation within an intricate bony labyrinth. As such, mammalian inner ear explants are an invaluable tool for the study and manipulation of the complex intercellular connections, structures, and cell types within this specialised organ. The greatest strength of this technique is that the complete organ of Corti, or peripheral vestibular organs including hair cells, supporting cells and accompanying neurons, is maintained in its in situ form. The greatest weakness of in vitro hair cell preparations is the short time frame in which the explanted tissue remains viable. Yet, cochlear explants have proven to be an excellent experimental model for understanding the fundamental aspects of auditory biology, substantiated by their use for over 40 years. In this protocol, we present a modernised inner ear explant technique that employs organotypic cell culture inserts and serum free media. This approach decreases the likelihood of explant damage by eliminating the need for adhesive substances. Serum free media also restricts excessive cellular outgrowth and inter-experimental variability, both of which are side effects of exogenous serum addition to cell cultures. The protocol described can be applied to culture both cochlear and vestibular explants from various mammals. Example outcomes are demonstrated by immunohistochemistry, hair cell quantification, and electrophysiological recordings to validate the versatility and viability of the protocol.
Collapse
Affiliation(s)
- Jacqueline M. Ogier
- Department of Genetics, The Murdoch Children's Research Institute, Parkville, VIC, Australia
- Department of Paediatrics, The University of Melbourne, Parkville, VIC, Australia
| | - Rachel A. Burt
- Department of Genetics, The Murdoch Children's Research Institute, Parkville, VIC, Australia
- Department of Paediatrics, The University of Melbourne, Parkville, VIC, Australia
- Department of Genetics, The University of Melbourne, Parkville, VIC, Australia
| | - Hannah R. Drury
- School of Biomedical Sciences and Pharmacy, The University of Newcastle, Callaghan, NSW, Australia
| | - Rebecca Lim
- School of Biomedical Sciences and Pharmacy, The University of Newcastle, Callaghan, NSW, Australia
| | - Bryony A. Nayagam
- Department of Audiology and Speech Pathology, The University of Melbourne, Parkville, VIC, Australia
- The Bionics Institute, East Melbourne, VIC, Australia
| |
Collapse
|
10
|
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.
Collapse
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
| |
Collapse
|
11
|
Dougherty MJ, Smith AT. Acute streptococcal meningitis presenting as bilateral conductive hearing loss. Am J Emerg Med 2018; 36:1324.e3-1324.e4. [DOI: 10.1016/j.ajem.2018.04.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Accepted: 04/04/2018] [Indexed: 11/25/2022] Open
|