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Deng J, Yao Z, Wang S, Zhang X, Zhan L, Wang T, Yu W, Zeng J, Wu J, Fu S, Wu S, Ouyang Y, Huang C. Uni-directional release of ibuprofen from an asymmetric fibrous membrane enables effective peritendinous anti-adhesion. J Control Release 2024; 372:251-264. [PMID: 38908755 DOI: 10.1016/j.jconrel.2024.06.046] [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: 12/16/2023] [Revised: 05/31/2024] [Accepted: 06/19/2024] [Indexed: 06/24/2024]
Abstract
Drug-loaded porous membranes have been deemed to be effective physicochemical barriers to separate postoperative adhesion-prone tissues in tendon healing. However, cell viability and subsequent tissue regeneration might be severely interfered with the unrestricted release and the locally excessive concentration of anti-inflammatory drugs. Herein, we report a double-layered membrane with sustained and uni-directional drug delivery features to prevent peritendinous adhesion without hampering the healing outcome. A vortex-assisted electrospinning system in combination with ibuprofen (IBU)-in-water emulsion was utilized to fabricate IBU-loaded poly-ʟ-lactic-acid (PLLA) fiber bundle membrane (PFB-IBU) as the anti-adhesion layer. The resultant highly porous structure, oleophilic and hydrophobic nature of PLLA fibers enabled in situ loading of IBU with a concentration gradient across the membrane thickness. Aligned collagen nanofibers were further deposited at the low IBU concentration side of the membrane for regulating cell growth and achieving uni-directional release of IBU. Drug release kinetics showed that the release amount of IBU from the high concentration side reached 79.32% at 14 d, while it was only 0.35% at the collagen side. Therefore, fibroblast proliferation at the high concentration side was successfully inhibited without affecting the oriented growth of tendon-derived stem cells at the other side. In vivo evaluation of the rat Achilles adhesion model confirmed the successful peritendinous anti-adhesion of our double-layered membrane, in that the macrophage recruitment, the inflammatory factor secretion and the deposition of pathological adhesion markers such as α-SMA and COL-III were all inhibited, which greatly improved the peritendinous fibrosis and restored the motor function of tendon.
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Affiliation(s)
- Jixia Deng
- Shanghai Frontiers Science Center of Advanced Textiles, College of Textiles, Donghua University, Shanghai 201620, China
| | - Zhixiao Yao
- Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 201620, China
| | - Shikun Wang
- Shanghai Frontiers Science Center of Advanced Textiles, College of Textiles, Donghua University, Shanghai 201620, China; Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 201620, China
| | - Xinyu Zhang
- Shanghai Frontiers Science Center of Advanced Textiles, College of Textiles, Donghua University, Shanghai 201620, China
| | - Lei Zhan
- Shanghai Frontiers Science Center of Advanced Textiles, College of Textiles, Donghua University, Shanghai 201620, China
| | - Tongyu Wang
- Shanghai Frontiers Science Center of Advanced Textiles, College of Textiles, Donghua University, Shanghai 201620, China
| | - Wenhua Yu
- Shanghai Frontiers Science Center of Advanced Textiles, College of Textiles, Donghua University, Shanghai 201620, China
| | - Jiamei Zeng
- Shanghai Frontiers Science Center of Advanced Textiles, College of Textiles, Donghua University, Shanghai 201620, China
| | - Jinglei Wu
- Biomaterials and Tissue Engineering Laboratory, College of Chemistry and Chemical Engineering and Biological Engineering, Donghua University, Shanghai 201620, China
| | - Shaoju Fu
- Shanghai Frontiers Science Center of Advanced Textiles, College of Textiles, Donghua University, Shanghai 201620, China
| | - Shihao Wu
- School of Medicine, Yunnan University, Kunming, Yunnan 650091, China.
| | - Yuanming Ouyang
- Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 201620, China.
| | - Chen Huang
- Shanghai Frontiers Science Center of Advanced Textiles, College of Textiles, Donghua University, Shanghai 201620, China.
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Vieira CP, Lelis CA, Ochioni AC, Rosário DKA, Rosario ILS, Vieira IRS, Carvalho APA, Janeiro JM, da Costa MP, Lima FRS, Mariante RM, Alves LA, Foguel D, Junior CAC. Estimating the therapeutic potential of NSAIDs and linoleic acid-isomers supplementation against neuroinflammation. Biomed Pharmacother 2024; 177:116884. [PMID: 38889635 DOI: 10.1016/j.biopha.2024.116884] [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: 02/07/2024] [Revised: 06/03/2024] [Accepted: 06/03/2024] [Indexed: 06/20/2024] Open
Abstract
Nonsteroidal anti-inflammatory drugs (NSAIDs) regulate inflammation, which is associated with their role in preventing neurodegenerative diseases in epidemiological studies. It has sparked interest in their unconventional application for reducing neuroinflammation, opening up new avenues in biomedical research. However, given the pharmacological drawbacks of NSAIDs, the development of formulations with naturally antioxidant/anti-inflammatory dietary fatty acids has been demonstrated to be advantageous for the clinical translation of anti-inflammatory-based therapies. It includes improved blood-brain barrier (BBB) permeability and reduced toxicity. It permits us to speculate about the value of linoleic acid (LA)-isomers in preventing and treating neuroinflammatory diseases compared to NSAIDs. Our research delved into the impact of various factors, such as administration route, dosage, timing of intervention, and BBB permeability, on the efficacy of NSAIDs and LA-isomers in preclinical and clinical settings. We conducted a systematic comparison between NSAIDs and LA-isomers regarding their therapeutic effectiveness, BBB compatibility, and side effects. Additionally, we explored their underlying mechanisms in addressing neuroinflammation. Through our analysis, we've identified challenges and drawn conclusions that could propel advancements in treating neurodegenerative diseases and inform the development of future alternative therapeutic strategies.
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Affiliation(s)
- Carla Paulo Vieira
- Laboratory of Advanced Analysis in Biochemistry and Molecular Biology (LAABBM), Department of Biochemistry, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ 21941-909, Brazil; Center for Food Analysis (NAL), Technological Development Support Laboratory (LADETEC), Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ 21941-598, Brazil; Cellular Communication Laboratory, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz (FIOCRUZ), Rio de Janeiro, RJ 21040-900, Brazil
| | - Carini A Lelis
- Laboratory of Advanced Analysis in Biochemistry and Molecular Biology (LAABBM), Department of Biochemistry, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ 21941-909, Brazil; Center for Food Analysis (NAL), Technological Development Support Laboratory (LADETEC), Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ 21941-598, Brazil
| | - Alan Clavelland Ochioni
- Laboratory of Advanced Analysis in Biochemistry and Molecular Biology (LAABBM), Department of Biochemistry, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ 21941-909, Brazil; Center for Food Analysis (NAL), Technological Development Support Laboratory (LADETEC), Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ 21941-598, Brazil
| | - Denes Kaic A Rosário
- Laboratory of Advanced Analysis in Biochemistry and Molecular Biology (LAABBM), Department of Biochemistry, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ 21941-909, Brazil; Center for Food Analysis (NAL), Technological Development Support Laboratory (LADETEC), Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ 21941-598, Brazil
| | - Iuri L S Rosario
- Center for Food Analysis (NAL), Technological Development Support Laboratory (LADETEC), Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ 21941-598, Brazil; Laboratory of Inspection and Technology of Milk and Derivatives (LaITLácteos), School of Veterinary Medicine and Zootechnies, Universidade Federal da Bahia (UFBA), Ondina, Salvador, BA 40170-110, Brazil
| | - Italo Rennan S Vieira
- Laboratory of Advanced Analysis in Biochemistry and Molecular Biology (LAABBM), Department of Biochemistry, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ 21941-909, Brazil; Center for Food Analysis (NAL), Technological Development Support Laboratory (LADETEC), Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ 21941-598, Brazil
| | - Anna Paula A Carvalho
- Laboratory of Advanced Analysis in Biochemistry and Molecular Biology (LAABBM), Department of Biochemistry, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ 21941-909, Brazil; Center for Food Analysis (NAL), Technological Development Support Laboratory (LADETEC), Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ 21941-598, Brazil
| | - José Marcos Janeiro
- Glial Cell Biology Laboratory, Institute of Biomedical Sciences, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ 21941-590, Brazil
| | - Marion P da Costa
- Laboratory of Inspection and Technology of Milk and Derivatives (LaITLácteos), School of Veterinary Medicine and Zootechnies, Universidade Federal da Bahia (UFBA), Ondina, Salvador, BA 40170-110, Brazil; Graduate Program in Food Science (PGAli), Faculty of Pharmacy, Universidade Federal da Bahia (UFBA), Ondina, Salvador, BA 40170-110, Brazil
| | - Flavia R S Lima
- Glial Cell Biology Laboratory, Institute of Biomedical Sciences, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ 21941-590, Brazil
| | - Rafael M Mariante
- Laboratory of Structural Biology, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz (Fiocruz), Rio de Janeiro, RJ 21040-900, Brazil
| | - Luiz Anastácio Alves
- Cellular Communication Laboratory, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz (FIOCRUZ), Rio de Janeiro, RJ 21040-900, Brazil
| | - Debora Foguel
- Laboratory of Protein Aggregation and Amyloidosis, Institute of Medical Biochemistry, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ 21941-590, Brazil
| | - Carlos Adam Conte Junior
- Laboratory of Advanced Analysis in Biochemistry and Molecular Biology (LAABBM), Department of Biochemistry, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ 21941-909, Brazil; Center for Food Analysis (NAL), Technological Development Support Laboratory (LADETEC), Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ 21941-598, Brazil.
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Gansemer BM, Rahman MT, Zhang Z, Green SH. Spiral ganglion neuron degeneration in aminoglycoside-deafened rats involves innate and adaptive immune responses not requiring complement. Front Mol Neurosci 2024; 17:1389816. [PMID: 38840777 PMCID: PMC11151750 DOI: 10.3389/fnmol.2024.1389816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Accepted: 04/29/2024] [Indexed: 06/07/2024] Open
Abstract
Spiral ganglion neurons (SGNs) transmit auditory information from cochlear hair cells to the brain. SGNs are thus not only important for normal hearing, but also for effective functioning of cochlear implants, which stimulate SGNs when hair cells are missing. SGNs slowly degenerate following aminoglycoside-induced hair cell loss, a process thought to involve an immune response. However, the specific immune response pathways involved remain unknown. We used RNAseq to gain a deeper understanding immune-related and other transcriptomic changes that occur in the rat spiral ganglion after kanamycin-induced deafening. Among the immune and inflammatory genes that were selectively upregulated in deafened spiral ganglia, the complement cascade genes were prominent. We then assessed SGN survival, as well as immune cell numbers and activation, in the spiral ganglia of rats with a CRISPR-Cas9-mediated knockout of complement component 3 (C3). Similar to previous findings in our lab and other deafened rodent models, we observed an increase in macrophage number and increased expression of CD68, a marker of phagocytic activity and cell activation, in macrophages in the deafened ganglia. Moreover, we found an increase in MHCII expression on spiral ganglion macrophages and an increase in lymphocyte number in the deafened ganglia, suggestive of an adaptive immune response. However, C3 knockout did not affect SGN survival or increase in macrophage number/activation, implying that complement activation does not play a role in SGN death after deafening. Together, these data suggest that both innate and adaptive immune responses are activated in the deafened spiral ganglion, with the adaptive response directly contributing to cochlear neurodegeneration.
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Affiliation(s)
| | | | | | - Steven H. Green
- Department of Biology, University of Iowa, Iowa City, IA, United States
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Nitta Y, Kurioka T, Mogi S, Sano H, Yamashita T. Suppression of the TGF-β signaling exacerbates degeneration of auditory neurons in kanamycin-induced ototoxicity in mice. Sci Rep 2024; 14:10910. [PMID: 38740884 DOI: 10.1038/s41598-024-61630-1] [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: 01/14/2024] [Accepted: 05/08/2024] [Indexed: 05/16/2024] Open
Abstract
Transforming growth factor-β (TGF-β) signaling plays a significant role in multiple biological processes, including inflammation, immunity, and cell death. However, its specific impact on the cochlea remains unclear. In this study, we aimed to investigate the effects of TGF-β signaling suppression on auditory function and cochlear pathology in mice with kanamycin-induced ototoxicity. Kanamycin and furosemide (KM-FS) were systemically administered to 8-week-old C57/BL6 mice, followed by immediate topical application of a TGF-β receptor inhibitor (TGF-βRI) onto the round window membrane. Results showed significant TGF-β receptor upregulation in spiral ganglion neurons (SGNs) after KM-FA ototoxicity, whereas expression levels in the TGF-βRI treated group remained unchanged. Interestingly, despite no significant change in cochlear TGF-β expression after KM-FS ototoxicity, TGF-βRI treatment resulted in a significant decrease in TGF-β signaling. Regarding auditory function, TGF-βRI treatment offered no therapeutic effects on hearing thresholds and hair cell survival following KM-FS ototoxicity. However, SGN loss and macrophage infiltration were significantly increased with TGF-βRI treatment. These results imply that inhibition of TGF-β signaling after KM-FS ototoxicity promotes cochlear inflammation and SGN degeneration.
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Affiliation(s)
- Yoshihiro Nitta
- Department of Otorhinolaryngology and Head and Neck Surgery, Kitasato University School of Medicine, 1-15-1 Kitasato, Minami-ku, Sagamihara, Kanagawa, 252-0374, Japan.
| | - Takaomi Kurioka
- Department of Otorhinolaryngology, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama, 359-8513, Japan.
| | - Sachiyo Mogi
- Department of Otorhinolaryngology and Head and Neck Surgery, Kitasato University School of Medicine, 1-15-1 Kitasato, Minami-ku, Sagamihara, Kanagawa, 252-0374, Japan
| | - Hajime Sano
- School of Allied Health Sciences, Kitasato University, Kanagawa, Japan
| | - Taku Yamashita
- Department of Otorhinolaryngology and Head and Neck Surgery, Kitasato University School of Medicine, 1-15-1 Kitasato, Minami-ku, Sagamihara, Kanagawa, 252-0374, Japan
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Li G, Gao Y, Wu H, Zhao T. Gentamicin administration leads to synaptic dysfunction in inner hair cells. Toxicol Lett 2024; 391:86-99. [PMID: 38101494 DOI: 10.1016/j.toxlet.2023.12.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Revised: 11/17/2023] [Accepted: 12/11/2023] [Indexed: 12/17/2023]
Abstract
Ototoxicity is a major side effect of aminoglycosides, which can cause irreversible hearing loss. Previous studies on aminoglycoside-induced ototoxicity have primarily focused on the loss of sensory hair cells. Recent investigations have revealed that aminoglycosides can also lead to the loss of ribbon synapses in inner hair cells (IHCs). However, the functional implications of ribbon synapse loss and the underlying mechanisms remain unclear. In this study, we intraperitoneally injected C57BL/6 J mice with 300 mg/kg gentamicin once daily for 3, 10, and 20 days. Then, we performed immunofluorescence staining, patch-clamp recording, proteomics analysis and western blotting to characterize the changes in ribbon synapses in IHCs and the associated mechanisms. After gentamicin treatment, the auditory brainstem response (ABR) threshold was elevated, and the ABR wave I amplitude was decreased. We also observed loss of ribbon synapses in IHCs. Interestingly, ribbon synapse loss occurred on both the modiolar and pillar sides of IHCs. Whole-cell patch-clamp recordings in IHCs revealed a reduction in the calcium current amplitude, along with a shifted half-activation voltage and altered calcium voltage dependency. Moreover, exocytosis of IHCs was reduced, consistent with the reduction in the ABR wave I amplitude. Through proteomic analysis, western blotting, and immunofluorescence staining, we found that gentamicin treatment resulted in downregulation of myosin VI, a protein crucial for synaptic vesicle recycling and replenishment in IHCs. Furthermore, we evaluated the kinetics of endocytosis and found a significant reduction in IHC exocytosis, possibly reflecting the impact of myosin VI downregulation on synaptic vesicle recycling. In summary, our findings demonstrate that gentamicin treatment leads to synaptic dysfunction in IHCs, highlighting the important role of myosin VI downregulation in gentamicin-induced synaptic damage.
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Affiliation(s)
- Gen Li
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Yunge Gao
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Hao Wu
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China.
| | - Ting Zhao
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China.
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Sridharan PS, Miller E, Pieper AA. Application of P7C3 Compounds to Investigating and Treating Acute and Chronic Traumatic Brain Injury. Neurotherapeutics 2023; 20:1616-1628. [PMID: 37651054 PMCID: PMC10684439 DOI: 10.1007/s13311-023-01427-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/16/2023] [Indexed: 09/01/2023] Open
Abstract
Traumatic brain injury (TBI) is a leading worldwide cause of disability, and there are currently no medicines that prevent, reduce, or reverse acute or chronic neurodegeneration in TBI patients. Here, we review the target-agnostic discovery of nicotinamide adenine dinucleotide (NAD+)/NADH-stabilizing P7C3 compounds through a phenotypic screen in mice and describe how P7C3 compounds have been applied to advance understanding of the pathophysiology and potential treatment of TBI. We summarize how P7C3 compounds have been shown across multiple laboratories to mitigate disease progression safely and effectively in a broad range of preclinical models of disease related to impaired NAD+/NADH metabolism, including acute and chronic TBI, and note the reported safety and neuroprotective efficacy of P7C3 compounds in nonhuman primates. We also describe how P7C3 compounds facilitated the recent first demonstration that chronic neurodegeneration 1 year after TBI in mice, the equivalent of many decades in people, can be reversed to restore normal neuropsychiatric function. We additionally review how P7C3 compounds have facilitated discovery of new pathophysiologic mechanisms of neurodegeneration after TBI. This includes the role of rapid TBI-induced tau acetylation that drives axonal degeneration, and the discovery of brain-derived acetylated tau as the first blood-based biomarker of neurodegeneration after TBI that directly correlates with the abundance of a therapeutic target in the brain. We additionally review the identification of TBI-induced tau acetylation as a potential mechanistic link between TBI and increased risk of Alzheimer's disease. Lastly, we summarize historical accounts of other successful phenotypic-based drug discoveries that advanced medical care without prior recognition of the specific molecular target needed to achieve the desired therapeutic effect.
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Affiliation(s)
- Preethy S Sridharan
- Brain Health Medicines Center, Harrington Discovery Institute, University Hospitals Cleveland Medical Center, Cleveland, OH, USA
- Department of Psychiatry, Case Western Reserve University, Cleveland, OH, USA
- Geriatric Psychiatry, GRECC, Louis Stokes Cleveland VA Medical Center, Cleveland, OH, USA
- Institute for Transformative Molecular Medicine, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Emiko Miller
- Brain Health Medicines Center, Harrington Discovery Institute, University Hospitals Cleveland Medical Center, Cleveland, OH, USA
- Department of Psychiatry, Case Western Reserve University, Cleveland, OH, USA
- Geriatric Psychiatry, GRECC, Louis Stokes Cleveland VA Medical Center, Cleveland, OH, USA
- Institute for Transformative Molecular Medicine, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Andrew A Pieper
- Brain Health Medicines Center, Harrington Discovery Institute, University Hospitals Cleveland Medical Center, Cleveland, OH, USA.
- Department of Psychiatry, Case Western Reserve University, Cleveland, OH, USA.
- Geriatric Psychiatry, GRECC, Louis Stokes Cleveland VA Medical Center, Cleveland, OH, USA.
- Institute for Transformative Molecular Medicine, School of Medicine, Case Western Reserve University, Cleveland, OH, USA.
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, OH, USA.
- Department of Pathology, School of Medicine, Case Western Reserve University, Cleveland, OH, USA.
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Rahman MT, Mostaert BJ, Hunger B, Saha U, Claussen AD, Razu I, Farjana N, Khan NA, Coleman S, Oleson J, Kirk J, Keiko H, Hansen MR. Contribution of macrophages to intracochlear tissue remodeling responses following cochlear implantation and neural survival. RESEARCH SQUARE 2023:rs.3.rs-3065630. [PMID: 37461619 PMCID: PMC10350110 DOI: 10.21203/rs.3.rs-3065630/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/24/2023]
Abstract
Introduction Cochlear implants (CIs) restore hearing to deafened patients. The foreign body response (FBR) following cochlear implantation (post-CI) comprises an infiltration of macrophages, other immune and non-immune cells, and fibrosis into the scala tympani; a space that is normally devoid of cells. This FBR is associated with negative effects on CI outcomes including increased electrode impedances and loss of residual acoustic hearing. This study investigates the extent to which macrophage depletion by an orally administered CSF-1R specific kinase (c-FMS) inhibitor, PLX-5622, modulates the tissue response to CI and neural health. Materials and methods 10-12-week-old CX3CR1+/GFP Thy1+/YFP mice on C57Bl6 background with normal hearing were fed chow containing 1200 mg/kg PLX5622 or control chow for the duration of the study. 7-days after starting the diet, 3-channel cochlear implants were implanted ear via the round window. Serial impedance and neural response telemetry (NRT) measurements were acquired throughout the study. Electric stimulation began 7 days post-CI until 28- days post-CI for 5 hrs/day, 5 days/week, with programming guided by NRT and behavioral responses. Cochleae harvested at 10-, 28- or 56-days post-CI were cryosectioned and labeled with antibody against α-smooth muscle actin (α-SMA) to identify myofibroblasts and quantify the fibrotic response. Using IMARIS image analysis software, the outlines of scala tympani, Rosenthal canal, modiolus and lateral wall for each turn were traced manually to measure region volume. Density of nuclei, CX3CR1+ macrophages, Thy1+ spiral ganglion neuron (SGN) numbers and ratio of volume of α-SMA+ space/volume of scala tympani were calculated. Results Cochlear implantation in control diet subjects caused infiltration of cells, including macrophages, into the cochlea: this response was initially diffuse throughout the cochlea and later localized to the scala tympani of the basal turn by 56-days post-CI. Fibrosis was evident in the scala tympani adjacent to the electrode array. Mice fed PLX5622 chow showed reduced macrophage infiltration throughout the implanted cochleae across all timepoints. However, scala tympani fibrosis was not reduced relative to control diet subjects. Further, mice treated with PLX5622 showed increased electrode impedances compared to controls. Finally, treatment with PLX5622 decreased SGN survival in implanted and contralateral cochleae. Discussion The data suggest that macrophages play an important role in modulating the intracochlear tissue response following CI and neural survival.
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Affiliation(s)
| | - Brain J Mostaert
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, IA
| | - Bryce Hunger
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, IA
| | - Utsow Saha
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, IA
| | | | - Ibrahim Razu
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, IA
| | - Nasrin Farjana
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, IA
| | - Nashwaan Ali Khan
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, IA
| | - Sarah Coleman
- Department of Statistics, The University of Iowa, IA
| | - Jackob Oleson
- Department of Statistics, The University of Iowa, IA
| | | | - Hirose Keiko
- Department of Otolaryngology-Head and Neck Surgery, Washington University School of Medicine, St Louis, MO
| | - Marlan R Hansen
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, IA
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