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Shi TF, Zhou Z, Jiang WJ, Huang TL, Si JQ, Li L. Hyperglycemia-induced oxidative stress exacerbates mitochondrial apoptosis damage to cochlear stria vascularis pericytes via the ROS-mediated Bcl-2/CytC/AIF pathway. Redox Rep 2024; 29:2382943. [PMID: 39092597 PMCID: PMC11299461 DOI: 10.1080/13510002.2024.2382943] [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] [Indexed: 08/04/2024] Open
Abstract
OBJECTIVES Diabetes is closely linked to hearing loss, yet the exact mechanisms remain unclear. Cochlear stria vascularis and pericytes (PCs) are crucial for hearing. This study investigates whether high glucose induces apoptosis in the cochlear stria vascularis and pericytes via elevated ROS levels due to oxidative stress, impacting hearing loss. METHODS We established a type II diabetes model in C57BL/6J mice and used auditory brainstem response (ABR), Evans blue staining, HE staining, immunohistochemistry, and immunofluorescence to observe changes in hearing, blood-labyrinth barrier (BLB) permeability, stria vascularis morphology, and apoptosis protein expression. Primary cultured stria vascularis pericytes were subjected to high glucose, and apoptosis levels were assessed using flow cytometry, Annexin V-FITC, Hoechst 33342 staining, Western blot, Mitosox, and JC-1 probes. RESULTS Diabetic mice showed decreased hearing thresholds, reduced stria vascularis density, increased oxidative stress, cell apoptosis, and decreased antioxidant levels. High glucose exposure increased apoptosis and ROS content in pericytes, while mitochondrial membrane potential decreased, with AIF and cytochrome C (CytC) released from mitochondria to the cytoplasm. Adding oxidative scavengers reduced AIF and CytC release, decreasing pericyte apoptosis. DISCUSSION Hyperglycemia may induce mitochondrial apoptosis of cochlear stria vascularis pericytes through oxidative stress.
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Affiliation(s)
- Tian-feng Shi
- Department of Physiology, Medical College of Jiaxing University, Jiaxing, Zhejiang, People's Republic of China
- Department of Physiology, Medical College of Shihezi University, Shihezi, Xinjiang, People's Republic of China
- The Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Medical College of Shihezi University, Shihezi, Xinjiang, People's Republic of China
| | - Zan Zhou
- Department of Physiology, Medical College of Jiaxing University, Jiaxing, Zhejiang, People's Republic of China
- Department of Physiology, Medical College of Shihezi University, Shihezi, Xinjiang, People's Republic of China
- The Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Medical College of Shihezi University, Shihezi, Xinjiang, People's Republic of China
| | - Wen-jun Jiang
- Department of Physiology, Medical College of Jiaxing University, Jiaxing, Zhejiang, People's Republic of China
- Department of Physiology, Zhejiang Chinese Medical University, Hangzhou, Zhejiang, People's Republic of China
| | - Tian-lan Huang
- Department of Physiology, Medical College of Shihezi University, Shihezi, Xinjiang, People's Republic of China
- The Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Medical College of Shihezi University, Shihezi, Xinjiang, People's Republic of China
| | - Jun-qiang Si
- Department of Physiology, Medical College of Shihezi University, Shihezi, Xinjiang, People's Republic of China
- The Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Medical College of Shihezi University, Shihezi, Xinjiang, People's Republic of China
| | - Li Li
- Department of Physiology, Medical College of Jiaxing University, Jiaxing, Zhejiang, People's Republic of China
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Wang Y, Nie J, Yan K, Wang J, Wang X, Zhao Y. Inflammatory diet, gut microbiota and sensorineural hearing loss: a cross-sectional and Mendelian randomization study. Front Nutr 2024; 11:1458484. [PMID: 39221159 PMCID: PMC11363541 DOI: 10.3389/fnut.2024.1458484] [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: 07/02/2024] [Accepted: 08/01/2024] [Indexed: 09/04/2024] Open
Abstract
Aims Inflammatory diets can trigger chronic inflammation and affect gut microbiota. However, the relationship between dietary preferences and sensorineural hearing loss (SNHL) remains unclear. This study aims to elucidate the relationship between different dietary preferences and sensorineural deafness. Methods The Dietary Inflammation Index (DII) and SNHL were defined by data from the National Health and Nutrition Examination Survey (NHANES), and exploring their relationship. Using Mendelian randomization (MR) to analyze the relationship between 34 dietary preferences, 211 gut microbiota, and SNHL. Results Smooth curve fitting indicated that the risk of SNHL increased with increasing DII score when the DII score was greater than 5.15. MR results suggest that a diet including both oily and non-oily fish can substantially reduce the risk of SNHL. Additionally, six specific gut microbiota were found to have significant causal relationship with SNHL. Conclusion An inflammatory diet may increase the risk of developing SNHL. The observed relationship between fish consumption, gut microbiota, and SNHL suggests the existence of a gut-inner ear axis.
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Affiliation(s)
- Yixuan Wang
- Department of Otolaryngology Head and Neck Surgery, Shaanxi Provincial People’s Hospital, Xi’an, China
| | - Jiayi Nie
- Xi’an University of Technology, Xi’an, China
| | - Kaige Yan
- Northwest A&F University, Yangling, China
| | - Jing Wang
- Department of Otolaryngology Head and Neck Surgery, Shaanxi Provincial People’s Hospital, Xi’an, China
| | - Xin Wang
- Department of Otolaryngology Head and Neck Surgery, Shaanxi Provincial People’s Hospital, Xi’an, China
| | - Yuxiang Zhao
- Department of Otolaryngology Head and Neck Surgery, Shaanxi Provincial People’s Hospital, Xi’an, China
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Cosentino A, Agafonova A, Modafferi S, Trovato Salinaro A, Scuto M, Maiolino L, Fritsch T, Calabrese EJ, Lupo G, Anfuso CD, Calabrese V. Blood-Labyrinth Barrier in Health and Diseases: Effect of Hormetic Nutrients. Antioxid Redox Signal 2024; 40:542-563. [PMID: 37565276 DOI: 10.1089/ars.2023.0251] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 08/12/2023]
Abstract
Significance: The stria vascularis, located in the inner ear, consists of three layers, one of which is the blood-labyrinth barrier (BLB). It is formed by endothelial cells, sealed together to prevent the passage of toxic substances from the blood to the inner ear, by pericytes and perivascular-resident macrophage-like melanocyte. Recent Advances: There are various causes that lead to hearing loss, and among these are noise-induced and autoimmune hearing loss, ear disorders related to ototoxic medication, Ménière's disease, and age-related hearing loss. For all of these, major therapeutic interventions include drug-loaded nanoparticles, via intratympanic or intracochlear delivery. Critical Issues: Since many pathologies associated with hearing loss are characterized by a weakening of the BLB, in this review, the molecular mechanisms underlying the response to damage of BLB cellular components have been discussed. In addition, insight into the role of hormetic nutrients against hearing loss pathology is proposed. Future Directions: BLB cellular components of neurovascular cochlear unit play important physiological roles, owing to their impermeable function against all ototoxic substances that can induce damage. Studies are needed to investigate the cross talk occurring between these cellular components to exploit their possible role as novel targets for therapeutic interventions that may unravel future path based on the use of hormetic nutrients. Antioxid. Redox Signal. 40, 542-563.
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Affiliation(s)
- Alessia Cosentino
- Section of Medical Biochemistry, Department of Biomedical and Biotechnological Sciences, School of Medicine; Surgical and Advanced Technologies "G. F. Ingrassia"; University of Catania, Catania, Italy
| | - Aleksandra Agafonova
- Section of Medical Biochemistry, Department of Biomedical and Biotechnological Sciences, School of Medicine; Surgical and Advanced Technologies "G. F. Ingrassia"; University of Catania, Catania, Italy
| | - Sergio Modafferi
- Section of Medical Biochemistry, Department of Biomedical and Biotechnological Sciences, School of Medicine; Surgical and Advanced Technologies "G. F. Ingrassia"; University of Catania, Catania, Italy
| | - Angela Trovato Salinaro
- Section of Medical Biochemistry, Department of Biomedical and Biotechnological Sciences, School of Medicine; Surgical and Advanced Technologies "G. F. Ingrassia"; University of Catania, Catania, Italy
| | - Maria Scuto
- Section of Medical Biochemistry, Department of Biomedical and Biotechnological Sciences, School of Medicine; Surgical and Advanced Technologies "G. F. Ingrassia"; University of Catania, Catania, Italy
| | - Luigi Maiolino
- Department of Medical, Surgical and Advanced Technologies "G. F. Ingrassia"; University of Catania, Catania, Italy
| | | | - Edward J Calabrese
- Department of Environmental Health, School of Public Health and Health Sciences, University of Massachusetts, Amherst, Massachusetts, USA
| | - Gabriella Lupo
- Section of Medical Biochemistry, Department of Biomedical and Biotechnological Sciences, School of Medicine; Surgical and Advanced Technologies "G. F. Ingrassia"; University of Catania, Catania, Italy
| | - Carmelina Daniela Anfuso
- Section of Medical Biochemistry, Department of Biomedical and Biotechnological Sciences, School of Medicine; Surgical and Advanced Technologies "G. F. Ingrassia"; University of Catania, Catania, Italy
| | - Vittorio Calabrese
- Section of Medical Biochemistry, Department of Biomedical and Biotechnological Sciences, School of Medicine; Surgical and Advanced Technologies "G. F. Ingrassia"; University of Catania, Catania, Italy
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Ohlemiller KK, Dwyer N, Henson V, Fasman K, Hirose K. A critical evaluation of "leakage" at the cochlear blood-stria-barrier and its functional significance. Front Mol Neurosci 2024; 17:1368058. [PMID: 38486963 PMCID: PMC10937559 DOI: 10.3389/fnmol.2024.1368058] [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: 01/09/2024] [Accepted: 02/16/2024] [Indexed: 03/17/2024] Open
Abstract
The blood-labyrinth-barrier (BLB) is a semipermeable boundary between the vasculature and three separate fluid spaces of the inner ear, the perilymph, the endolymph and the intrastrial space. An important component of the BLB is the blood-stria-barrier, which shepherds the passage of ions and metabolites from strial capillaries into the intrastrial space. Some investigators have reported increased "leakage" from these capillaries following certain experimental interventions, or in the presence of inflammation or genetic variants. This leakage is generally thought to be harmful to cochlear function, principally by lowering the endocochlear potential (EP). Here, we examine evidence for this dogma. We find that strial capillaries are not exclusive, and that the asserted detrimental influence of strial capillary leakage is often confounded by hair cell damage or intrinsic dysfunction of the stria. The vast majority of previous reports speculate about the influence of strial vascular barrier function on the EP without directly measuring the EP. We argue that strial capillary leakage is common across conditions and species, and does not significantly impact the EP or hearing thresholds, either on evidentiary or theoretical grounds. Instead, strial capillary endothelial cells and pericytes are dynamic and allow permeability of varying degrees in response to specific conditions. We present observations from mice and demonstrate that the mechanisms of strial capillary transport are heterogeneous and inconsistent among inbred strains.
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Affiliation(s)
- Kevin K. Ohlemiller
- Department of Otolaryngology, Washington University School of Medicine, St. Louis, MO, United States
- Program in Communication Sciences and Audiology, Washington University School of Medicine, St. Louis, MO, United States
| | - Noël Dwyer
- Program in Communication Sciences and Audiology, Washington University School of Medicine, St. Louis, MO, United States
| | - Veronica Henson
- Program in Communication Sciences and Audiology, Washington University School of Medicine, St. Louis, MO, United States
| | - Kaela Fasman
- Program in Communication Sciences and Audiology, Washington University School of Medicine, St. Louis, MO, United States
| | - Keiko Hirose
- Department of Otolaryngology, Washington University School of Medicine, St. Louis, MO, United States
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Liu YC, Xu K. Macrophage-related immune responses in inner ear: a potential therapeutic target for sensorineural hearing loss. Front Neurosci 2024; 17:1339134. [PMID: 38274500 PMCID: PMC10808290 DOI: 10.3389/fnins.2023.1339134] [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: 11/15/2023] [Accepted: 12/22/2023] [Indexed: 01/27/2024] Open
Abstract
Hearing loss is the most common sensory disorder in human beings. Cochlear sensory cells are the basis of hearing. Cochlear sensory cells suffer from various acute or chronic injuries, such as excessive sound stimulation, ototoxic drugs, and age-related degeneration. In response to these stresses, the cochlea develops an immune response. In recent years, studies have shown that the immune response of the inner ear has been regarded as one of the important pathological mechanisms of inner ear injury. Therapeutic interventions for inflammatory responses can effectively alleviate different types of inner ear injury. As the main immune cells in the inner ear, macrophages are involved in the process of inner ear injury caused by various exogenous factors. However, its specific role in the immune response of the inner ear is still unclear. This review focuses on discusses the dynamic changes of macrophages during different types of inner ear injury, and clarifies the potential role of macrophage-related immune response in inner ear injury.
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Affiliation(s)
- Yu-Chen Liu
- Queen Mary School, Jiangxi Medical College, Nanchang University, Nanchang, China
| | - Kai Xu
- Department of Otolaryngology, Head and Neck Surgery, The Second Affiliated Hospital of Nanchang University, Jiangxi Medical College, Nanchang University, Nanchang, China
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Gao Y, Tian X, Zhang X, Milebe Nkoua GD, Chen F, Liu Y, Chai Y. The roles of tissue-resident macrophages in sepsis-associated organ dysfunction. Heliyon 2023; 9:e21391. [PMID: 38027963 PMCID: PMC10643296 DOI: 10.1016/j.heliyon.2023.e21391] [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: 06/26/2023] [Revised: 10/13/2023] [Accepted: 10/20/2023] [Indexed: 12/01/2023] Open
Abstract
Sepsis, a syndrome caused by a dysregulated host response to infection and characterized by life-threatening organ dysfunction, particularly septic shock and sepsis-associated organ dysfunction (SAOD), is a medical emergency associated with high morbidity, high mortality, and long-term sequelae. Tissue-resident macrophages (TRMs) are a subpopulation of macrophages derived primarily from yolk sac progenitors and fetal liver during embryogenesis, located primarily in non-lymphoid tissues in adulthood, capable of local self-renewal independent of hematopoiesis, and developmentally and functionally restricted to the non-lymphoid organs in which they reside. TRMs are the first line of defense against life-threatening conditions such as sepsis, tumor growth, traumatic-associated organ injury, and surgical-associated injury. In the context of sepsis, TRMs can be considered as angels or demons involved in organ injury. Our proposal is that sepsis, septic shock, and SAOD can be attenuated by modulating TRMs in different organs. This review summarizes the pathophysiological mechanisms of TRMs in different organs or tissues involved in the development and progression of sepsis.
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Affiliation(s)
- Yulei Gao
- Department of Emergency Medicine, Tianjin Medical University General Hospital, Tianjin, 300052, P. R. China
- Department of Emergency Medicine, China-Congo Friendship Hospital, Brazzaville, 999059, P. R. Congo
| | - Xin Tian
- Department of Medical Research, Beijing Qiansong Technology Development Company, Beijing, 100193, P. R. China
- Department of Medical Research, Sen Sho Ka Gi Company, Inba-gun, Chiba, 285-0905, Japan
| | - Xiang Zhang
- Department of Emergency Medicine, Rizhao People's Hospital of Shandong Province, Rizhao, 276825, P. R. China
| | | | - Fang Chen
- Department of Emergency Medicine, Tianjin Medical University General Hospital, Tianjin, 300052, P. R. China
| | - Yancun Liu
- Department of Emergency Medicine, Tianjin Medical University General Hospital, Tianjin, 300052, P. R. China
| | - Yanfen Chai
- Department of Emergency Medicine, Tianjin Medical University General Hospital, Tianjin, 300052, P. R. China
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7
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Chen CP, Chen PC, Pan YL, Hsu YC. Prenatal lipopolysaccharide exposure induces anxiety-like behaviour in male mouse offspring and aberrant glial differentiation of embryonic neural stem cells. Cell Mol Biol Lett 2023; 28:67. [PMID: 37592237 PMCID: PMC10436442 DOI: 10.1186/s11658-023-00480-7] [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: 03/09/2023] [Accepted: 07/26/2023] [Indexed: 08/19/2023] Open
Abstract
BACKGROUND Prenatal infection has been implicated in the development of neuropsychiatric disorders in children. We hypothesised that exposure to lipopolysaccharide during prenatal development could induce anxiety-like behaviour and sensorineural hearing loss in offspring, as well as disrupt neural differentiation during embryonic neural development. METHODS We simulated prenatal infection in FVB mice and mouse embryonic stem cell (ESC) lines, specifically 46C and E14Tg2a, through lipopolysaccharide treatment. Gene expression profiling analyses and behavioural tests were utilized to study the effects of lipopolysaccharide on the offspring and alterations in toll-like receptor (TLR) 2-positive and TLR4-positive cells during neural differentiation in the ESCs. RESULTS Exposure to lipopolysaccharide (25 µg/kg) on gestation day 9 resulted in anxiety-like behaviour specifically in male offspring, while no effects were detected in female offspring. We also found significant increases in the expression of GFAP and CNPase, as well as higher numbers of GFAP + astrocytes and O4+ oligodendrocytes in the prefrontal cortex of male offspring. Furthermore, increased scores for genes related to oligodendrocyte and lipid metabolism, particularly ApoE, were observed in the prefrontal cortex regions. Upon exposure to lipopolysaccharide during the ESC-to-neural stem cell (NSC) transition, Tuj1, Map2, Gfap, O4, and Oligo2 mRNA levels increased in the differentiated neural cells on day 14. In vitro experiments demonstrated that lipopolysaccharide exposure induced inflammatory responses, as evidenced by increased expression of IL1b and ApoB mRNA. CONCLUSIONS Our findings suggest that prenatal infection at different stages of neural differentiation may result in distinct disturbances in neural differentiation during ESC-NSC transitions. Furthermore, early prenatal challenges with lipopolysaccharide selectively induce anxiety-like behaviour in male offspring. This behaviour may be attributed to the abnormal differentiation of astrocytes and oligodendrocytes in the brain, potentially mediated by ApoB/E signalling pathways in response to inflammatory stimuli.
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Affiliation(s)
- Chie-Pein Chen
- Division of High Risk Pregnancy, Department of Obstetrics and Gynecology, MacKay Memorial Hospital, Taipei, Taiwan
- Department of Medical Research, MacKay Memorial Hospital, Taipei, Taiwan
| | - Pei-Chun Chen
- Department of Medical Research, MacKay Memorial Hospital, Taipei, Taiwan
| | - Yu-Ling Pan
- Department of Audiology and Speech-Language Pathology, MacKay Medical College, New Taipei City, Taiwan
| | - Yi-Chao Hsu
- Department of Audiology and Speech-Language Pathology, MacKay Medical College, New Taipei City, Taiwan.
- Institute of Biomedical Sciences, MacKay Medical College, New Taipei City, Taiwan.
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8
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Creber NJ, Eastwood HT, Hampson AJ, O'Leary SJ. Cochlear implant surgery facilitates intracochlear distribution of perioperative systemic steroids. Acta Otolaryngol 2023; 143:647-654. [PMID: 37603289 DOI: 10.1080/00016489.2023.2241877] [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: 05/11/2023] [Revised: 07/17/2023] [Accepted: 07/18/2023] [Indexed: 08/22/2023]
Abstract
BACKGROUND Systemically administered steroids are widely utilised for hearing preservation therapies. More recently, steroids have been administered to achieve hearing protection after cochlear implant surgery. Currently there is a lack of understanding as to which administration route offers most therapeutic efficacy, local or systemic administration. Paramount to this are observations in animal studies that systemic administration following implantation offers hearing protection and reduced cochlear fibrosis, despite observations that perilymphatic levels are up to 10-fold higher after local administration in non-implanted cochleae. AIMS/OBJECTIVES This paper explores the impact that cochlear implantation and associated acute inflammation has on steroid distribution and uptake following systemic administration of dexamethasone. MATERIAL AND METHODS Eight guinea pigs received systemic dexamethasone 60 min prior to cochlear implantation. Implanted and contralateral non-implanted cochlea were harvested for tissue immunohistochemistry and detection of dexamethasone. RESULTS Cochleostomy with scala tympani implantation resulted in a significant increase in cochlear dexamethasone signal. This was most notable at the organ of Corti, stria vascularis, and blood product in the scala tympani. CONCLUSIONS AND SIGNIFICANCE This study demonstrates that the inner ear distribution of systemically administered steroids is enhanced following surgery for cochlear implantation and provides rationale for systemic perioperative steroids in hearing preservation surgery.
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Affiliation(s)
- Nathan J Creber
- Otolaryngology, Department of Surgery, University of Melbourne, East Melbourne, Victoria, Australia
| | - Hayden T Eastwood
- Otolaryngology, Department of Surgery, University of Melbourne, East Melbourne, Victoria, Australia
| | - Amy J Hampson
- Otolaryngology, Department of Surgery, University of Melbourne, East Melbourne, Victoria, Australia
| | - Stephen J O'Leary
- Otolaryngology, Department of Surgery, University of Melbourne, East Melbourne, Victoria, Australia
- Royal Victorian Eye and Ear Hospital, East Melbourne, Victoria, Australia
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Balouch B, Meehan R, Suresh A, Zaheer HA, Jabir AR, Qatanani AM, Suresh V, Kaleem SZ, McKinnon BJ. Use of biologics for treatment of autoimmune inner ear disease. Am J Otolaryngol 2022; 43:103576. [DOI: 10.1016/j.amjoto.2022.103576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Revised: 07/21/2022] [Accepted: 07/31/2022] [Indexed: 11/01/2022]
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10
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Kociszewska D, Vlajkovic S. Age-Related Hearing Loss: The Link between Inflammaging, Immunosenescence, and Gut Dysbiosis. Int J Mol Sci 2022; 23:7348. [PMID: 35806352 PMCID: PMC9266910 DOI: 10.3390/ijms23137348] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Revised: 06/30/2022] [Accepted: 06/30/2022] [Indexed: 12/12/2022] Open
Abstract
This article provides a theoretical overview of the association between age-related hearing loss (ARHL), immune system ageing (immunosenescence), and chronic inflammation. ARHL, or presbyacusis, is the most common sensory disability that significantly reduces the quality of life and has a high economic impact. This disorder is linked to genetic risk factors but is also influenced by a lifelong cumulative effect of environmental stressors, such as noise, otological diseases, or ototoxic drugs. Age-related hearing loss and other age-related disorders share common mechanisms which often converge on low-grade chronic inflammation known as "inflammaging". Various stimuli can sustain inflammaging, including pathogens, cell debris, nutrients, and gut microbiota. As a result of ageing, the immune system can become defective, leading to the accumulation of unresolved inflammatory processes in the body. Gut microbiota plays a central role in inflammaging because it can release inflammatory mediators and crosstalk with other organ systems. A proinflammatory gut environment associated with ageing could result in a leaky gut and the translocation of bacterial metabolites and inflammatory mediators to distant organs via the systemic circulation. Here, we postulate that inflammaging, as a result of immunosenescence and gut dysbiosis, accelerates age-related cochlear degeneration, contributing to the development of ARHL. Age-dependent gut dysbiosis was included as a hypothetical link that should receive more attention in future studies.
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Affiliation(s)
| | - Srdjan Vlajkovic
- Department of Physiology and The Eisdell Moore Centre, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag, Auckland 1142, New Zealand;
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Zhang J, Fan W, Neng L, Chen B, Wang Y, Zuo B, Lu W. Adenosine improves LPS-induced ROS expression and increasing in monolayer permeability of endothelial cell via acting on A2AR. Microvasc Res 2022; 143:104403. [PMID: 35753505 DOI: 10.1016/j.mvr.2022.104403] [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: 12/22/2021] [Revised: 05/23/2022] [Accepted: 06/20/2022] [Indexed: 11/19/2022]
Abstract
Blood-labyrinth barrier (BLB) disruption plays a crucial role in the development of otitis media. The aims of our study was to explore the role and action mechanism of adenosine in LPS-induced endothelial cells (ECs) damage, which are one of the major principal cell type for blood-labyrinth barrier (BLB), and so as to assess the potential of adenosine to be used in the treatment of BLB disruption in animal experiment. In our study, ECs were treated with LPS to mimic BLB damage in vitro. Our data showed that adenosine at dosage of 1, 10, and 20 μM had no influence on the cell viability of ECs. LPS treatment obviously suppressed the expression of Occludin and Zonula occludens-1 (ZO-1) in ECs, which was partly recused by adenosine treatment. Meantime, LPS-induced increasing in reactive oxygen species (ROS) production and ECs permeability also was rescued by adenosine treatment. However, inhibition the A2A receptor (A2AR) could attenuate the influence of adenosine on LPS-treated ECs, indicating that adenosine alleviated LPS-induced BLB damage by activating A2AR. Moreover, the inhibition of adenosine to LPS-induced inactivation of AMPK/AKT signaling pathway was partly recused by A2AR suppression. In addition, Compound C (an AMPK inhibitor) decreased the expression of Occludin and ZO-1 in ECs following LPS combined with adenosine treatment. In conclusion, adenosine alleviates LPS-induced BLB damage via AMPK/AKT pathway through activation of A2AR. This work suggests that adenosine may be a candidate drug for the treatment of BLB dysfunction-related diseases.
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Affiliation(s)
- Jinhui Zhang
- Department of otorhinolaryngology, Head and Neck surgery, The First Affiliated Hospital of Zhengzhou University, No 1 Jianshe Road, Zhengzhou 450052, Henan, China.
| | - Wenya Fan
- Department of otorhinolaryngology, Head and Neck surgery, The First Affiliated Hospital of Zhengzhou University, No 1 Jianshe Road, Zhengzhou 450052, Henan, China
| | - Lingling Neng
- Department of otorhinolaryngology, Head and Neck surgery, The First Affiliated Hospital of Zhengzhou University, No 1 Jianshe Road, Zhengzhou 450052, Henan, China
| | - Bei Chen
- Department of otorhinolaryngology, Head and Neck surgery, The First Affiliated Hospital of Zhengzhou University, No 1 Jianshe Road, Zhengzhou 450052, Henan, China
| | - Yanting Wang
- Department of Anesthesiology, The Affiliated Hospital of Qingdao University, No 16, Jiangsu Road, Qingdao, Shandong, China
| | - Bin Zuo
- Department of otorhinolaryngology, Head and Neck surgery, The First Affiliated Hospital of Zhengzhou University, No 1 Jianshe Road, Zhengzhou 450052, Henan, China
| | - Wei Lu
- Department of otorhinolaryngology, Head and Neck surgery, The First Affiliated Hospital of Zhengzhou University, No 1 Jianshe Road, Zhengzhou 450052, Henan, China.
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12
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Lee SY, Kim S, Han K, Woong Choi J, Byung Chae H, Yeon Choi D, Min Lee S, Kyun Park M, Mun S, Koo JW. Microarray analysis of lipopolysaccharide-induced endotoxemia in the cochlea. Gene 2022; 823:146347. [PMID: 35227853 DOI: 10.1016/j.gene.2022.146347] [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: 09/29/2021] [Revised: 02/06/2022] [Accepted: 02/15/2022] [Indexed: 11/24/2022]
Abstract
Lipopolysaccharide (LPS)-induced endotoxemia alters intracochlear homeostasis and potentiates aminoglycoside-induced ototoxicity. However, the pathological mechanisms in the cochlea following systemic LPS-induced inflammation are unclear. In this study, three groups of mice received intraperitoneal injections [group A, saline control (n = 10); group B, 1 mg/kg LPS (n = 10); group C, 10 mg/kg LPS (n = 10)]. After 24 h, gene expression in cochlea samples was analyzed using DNA microarrays covering 28,853 genes in a duplicate manner. A total of 505 differentially expressed genes (DEGs) (≥2.0-fold change; p < 0.05) were identified. Interferon- and chemotaxis-related genes, including gbp2, gbp5, cxcl10, and Rnf125, were dose-dependently upregulated by LPS-induced endotoxemia. These results were verified by RT-qPCR. Upregulated DEGs were associated with inflammation, positive regulation of immune responses, and regulation of cell adhesion, while downregulated ones were associated with chemical synaptic transmission and the synaptic vesicle cycle. Protein-protein interaction included four functional clusters associated with interleukin-4, -10, and -13 and G protein-coupled receptor (GPCR) ligand binding; activation of matrix metalloproteinases and collagen degradation; recruitment of amyloid A proteins; and neutrophil degranulation. The findings of this study provide an additional basis on changes in the expression of genes in the cochlea in response to LPS-induced endotoxemia.
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Affiliation(s)
- Sang-Yeon Lee
- Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, South Korea; Sensory Organ Research Institute, Seoul National University Medical Research Center, South Korea
| | - Songmi Kim
- Center for Bio-Medical Engineering Core Facility, Dankook University, Cheonan 31116, South Korea; Department of Microbiology, College of Science and Technology, Dankook University, Cheonan 31116, South Korea
| | - Kyudong Han
- Center for Bio-Medical Engineering Core Facility, Dankook University, Cheonan 31116, South Korea; Department of Microbiology, College of Science and Technology, Dankook University, Cheonan 31116, South Korea
| | - Jin Woong Choi
- Department of Otorhinolaryngology-Head and Neck Surgery, Chungnam National University, College of Medicine, Daejeon, South Korea
| | - Ho Byung Chae
- Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, South Korea
| | - Da Yeon Choi
- Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, South Korea
| | - So Min Lee
- Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, South Korea
| | - Moo Kyun Park
- Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, South Korea
| | - Seyoung Mun
- Center for Bio-Medical Engineering Core Facility, Dankook University, Cheonan 31116, South Korea; Department of Nanobiomedical Science & BK21 PLUS NBM Global Research Center for Regenerative Medicine, Dankook University, Cheonan 31116, South Korea.
| | - Ja-Won Koo
- Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, South Korea; Sensory Organ Research Institute, Seoul National University Medical Research Center, South Korea.
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13
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Chan J, Telang R, Kociszewska D, Thorne PR, Vlajkovic SM. A High-Fat Diet Induces Low-Grade Cochlear Inflammation in CD-1 Mice. Int J Mol Sci 2022; 23:5179. [PMID: 35563572 PMCID: PMC9101486 DOI: 10.3390/ijms23095179] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Revised: 05/02/2022] [Accepted: 05/04/2022] [Indexed: 02/04/2023] Open
Abstract
There is growing evidence for a relationship between gut dysbiosis and hearing loss. Inflammatory bowel disease, diet-induced obesity (DIO), and type 2 diabetes have all been linked to hearing loss. Here, we investigated the effect of a chronic high-fat diet (HFD) on the development of inner ear inflammation using a rodent model. Three-week-old CD-1 (Swiss) mice were fed an HFD or a control diet for ten weeks. After ten weeks, mouse cochleae were harvested, and markers of cochlear inflammation were assessed at the protein level using immunohistochemistry and at the gene expression level using quantitative real-time RT-PCR. We identified increased immunoexpression of pro-inflammatory biomarkers in animals on an HFD, including intracellular adhesion molecule 1 (ICAM1), interleukin 6 receptor α (IL6Rα), and toll-like-receptor 2 (TLR2). In addition, increased numbers of ionized calcium-binding adapter molecule 1 (Iba1) positive macrophages were found in the cochlear lateral wall in mice on an HFD. In contrast, gene expression levels of inflammatory markers were not affected by an HFD. The recruitment of macrophages to the cochlea and increased immunoexpression of inflammatory markers in mice fed an HFD provide direct evidence for the association between HFD and cochlear inflammation.
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Affiliation(s)
| | | | | | | | - Srdjan M. Vlajkovic
- Department of Physiology and The Eisdell Moore Centre, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand; (J.C.); (R.T.); (D.K.); (P.R.T.)
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14
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Kociszewska D, Chan J, Thorne PR, Vlajkovic SM. The Link between Gut Dysbiosis Caused by a High-Fat Diet and Hearing Loss. Int J Mol Sci 2021; 22:13177. [PMID: 34947974 PMCID: PMC8708400 DOI: 10.3390/ijms222413177] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 12/02/2021] [Accepted: 12/06/2021] [Indexed: 12/17/2022] Open
Abstract
This review aims to provide a conceptual and theoretical overview of the association between gut dysbiosis and hearing loss. Hearing loss is a global health issue; the World Health Organisation (WHO) estimates that 2.5 billion people will be living with some degree of hearing loss by 2050. The aetiology of sensorineural hearing loss (SNHL) is complex and multifactorial, arising from congenital and acquired causes. Recent evidence suggests that impaired gut health may also be a risk factor for SNHL. Inflammatory bowel disease (IBD), type 2 diabetes, diet-induced obesity (DIO), and high-fat diet (HFD) all show links to hearing loss. Previous studies have shown that a HFD can result in microangiopathy, impaired insulin signalling, and oxidative stress in the inner ear. A HFD can also induce pathological shifts in gut microbiota and affect intestinal barrier (IB) integrity, leading to a leaky gut. A leaky gut can result in chronic systemic inflammation, which may affect extraintestinal organs. Here, we postulate that changes in gut microbiota resulting from a chronic HFD and DIO may cause a systemic inflammatory response that can compromise the permeability of the blood-labyrinth barrier (BLB) in the inner ear, thus inducing cochlear inflammation and hearing deficits.
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Affiliation(s)
| | | | | | - Srdjan M. Vlajkovic
- Department of Physiology and The Eisdell Moore Centre, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag, Auckland 1142, New Zealand; (D.K.); (J.C.); (P.R.T.)
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15
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Zhang Y, Li Y, Fu X, Wang P, Wang Q, Meng W, Wang T, Yang J, Chai R. The Detrimental and Beneficial Functions of Macrophages After Cochlear Injury. Front Cell Dev Biol 2021; 9:631904. [PMID: 34458249 PMCID: PMC8385413 DOI: 10.3389/fcell.2021.631904] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2020] [Accepted: 07/14/2021] [Indexed: 12/20/2022] Open
Abstract
Macrophages are the main intrinsic immune cells in the cochlea; they can be activated and play a complicated role after cochlear injury. Many studies have shown that the number of macrophages and their morphological characteristics within the major cochlear partitions undergo significant changes under various pathological conditions including acoustic trauma, ototoxic drug treatment, age-related cochlear degeneration, selective hair cell (HC) and spiral ganglion neuron (SGN) elimination, and surgery. However, the exact role of these macrophages after cochlear injury is still unclear. Regulating the migration and activity of macrophages may be a therapeutic approach to reduce the risk or magnitude of trauma-induced hearing loss, and this review highlights the role of macrophages on the peripheral auditory structures of the cochlea and elucidate the mechanisms of macrophage injury and the strategies to reduce the injury by regulating macrophage.
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Affiliation(s)
- Yuan Zhang
- MOE Key Laboratory for Developmental Genes and Human Disease, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, School of Life Sciences and Technology, Southeast University, Nanjing, China.,Department of Otolaryngology Head and Neck, Nanjing Tongren Hospital, School of Medicine, Southeast University, Nanjing, China.,Co-innovation Center of Neuroregeneration, Nantong University, Nantong, China
| | - Yiyuan Li
- MOE Key Laboratory for Developmental Genes and Human Disease, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, School of Life Sciences and Technology, Southeast University, Nanjing, China
| | - Xiaolong Fu
- MOE Key Laboratory for Developmental Genes and Human Disease, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, School of Life Sciences and Technology, Southeast University, Nanjing, China
| | - Pengjun Wang
- Department of Otorhinolaryngology, Affiliated Sixth People's Hospital of Shanghai Jiao Tong University, Shanghai, China
| | - Qin Wang
- Department of Otolaryngology-Head and Neck Surgery, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Wei Meng
- Department of Otolaryngology Head and Neck, Nanjing Tongren Hospital, School of Medicine, Southeast University, Nanjing, China
| | - Tian Wang
- Department of Otolaryngology-Head and Neck Surgery, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Jianming Yang
- Department of Otorhinolaryngology, The Second Affiliated Hospital of Anhui Medical University, Hefei, China
| | - Renjie Chai
- MOE Key Laboratory for Developmental Genes and Human Disease, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, School of Life Sciences and Technology, Southeast University, Nanjing, China.,Co-innovation Center of Neuroregeneration, Nantong University, Nantong, China.,Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing, China
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16
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Hayashi Y, Suzuki H, Nakajima W, Uehara I, Tanimura A, Himeda T, Koike S, Katsuno T, Kitajiri SI, Koyanagi N, Kawaguchi Y, Onomoto K, Kato H, Yoneyama M, Fujita T, Tanaka N. Cochlear supporting cells function as macrophage-like cells and protect audiosensory receptor hair cells from pathogens. Sci Rep 2020; 10:6740. [PMID: 32317718 PMCID: PMC7174420 DOI: 10.1038/s41598-020-63654-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 04/01/2020] [Indexed: 12/25/2022] Open
Abstract
To protect the audiosensory organ from tissue damage from the immune system, the inner ear is separated from the circulating immune system by the blood-labyrinth barrier, which was previously considered an immune-privileged site. Recent studies have shown that macrophages are distributed in the cochlea, especially in the spiral ligament, spiral ganglion, and stria vascularis; however, the direct pathogen defence mechanism used by audiosensory receptor hair cells (HCs) has remained obscure. Here, we show that HCs are protected from pathogens by surrounding accessory supporting cells (SCs) and greater epithelial ridge (GER or Kölliker’s organ) cells (GERCs). In isolated murine cochlear sensory epithelium, we established Theiler’s murine encephalomyelitis virus, which infected the SCs and GERCs, but very few HCs. The virus-infected SCs produced interferon (IFN)-α/β, and the viruses efficiently infected the HCs in the IFN-α/β receptor-null sensory epithelium. Interestingly, the virus-infected SCs and GERCs expressed macrophage marker proteins and were eliminated from the cell layer by cell detachment. Moreover, lipopolysaccharide induced phagocytosis of the SCs without cell detachment, and the SCs phagocytosed the bacteria. These results reveal that SCs function as macrophage-like cells, protect adjacent HCs from pathogens, and provide a novel anti-infection inner ear immune system.
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Affiliation(s)
- Yushi Hayashi
- Department of Molecular Oncology, Institute for Advanced Medical Sciences, Nippon Medical School, Tokyo, Japan
| | - Hidenori Suzuki
- Division of Morphological and Biomolecular Research, Nippon Medical School, Tokyo, Japan
| | - Wataru Nakajima
- Department of Molecular Oncology, Institute for Advanced Medical Sciences, Nippon Medical School, Tokyo, Japan
| | - Ikuno Uehara
- Department of Molecular Oncology, Institute for Advanced Medical Sciences, Nippon Medical School, Tokyo, Japan
| | - Atsuko Tanimura
- Department of Molecular Oncology, Institute for Advanced Medical Sciences, Nippon Medical School, Tokyo, Japan
| | - Toshiki Himeda
- Department of Microbiology, Kanazawa Medical University School of Medicine, Ishikawa, Japan
| | - Satoshi Koike
- Neurovirology Project, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Tatsuya Katsuno
- Department of Otolaryngology, Head and Neck Surgery, Kyoto University, Kyoto, Japan
| | - Shin-Ichiro Kitajiri
- Department of Otolaryngology, Head and Neck Surgery, Kyoto University, Kyoto, Japan
| | - Naoto Koyanagi
- Division of Molecular Virology, Department of Microbiology and Immunology, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - Yasushi Kawaguchi
- Division of Molecular Virology, Department of Microbiology and Immunology, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - Koji Onomoto
- Division of Molecular Immunology, Medical Mycology Research Center, Chiba University, Chiba, Japan
| | - Hiroki Kato
- Laboratory of Molecular Genetics, Institute for Virus Research, Kyoto University, Kyoto, Japan
| | - Mitsutoshi Yoneyama
- Division of Molecular Immunology, Medical Mycology Research Center, Chiba University, Chiba, Japan
| | - Takashi Fujita
- Laboratory of Molecular Genetics, Institute for Virus Research, Kyoto University, Kyoto, Japan
| | - Nobuyuki Tanaka
- Department of Molecular Oncology, Institute for Advanced Medical Sciences, Nippon Medical School, Tokyo, Japan.
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17
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Dufek B, Meehan DT, Delimont D, Samuelson G, Madison J, Shi X, Boettcher F, Trosky V, Gratton MA, Cosgrove D. Pericyte abnormalities precede strial capillary basement membrane thickening in Alport mice. Hear Res 2020; 390:107935. [PMID: 32234583 DOI: 10.1016/j.heares.2020.107935] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 02/05/2020] [Accepted: 03/02/2020] [Indexed: 01/08/2023]
Abstract
In 129 Sv autosomal Alport mice, the strial capillary basement membranes (SCBMs) progressively thicken between 5 and 9 weeks of age resulting in a hypoxic microenvironment with metabolic stress and induction of pro-inflammatory cytokines and chemokines. These events occur concomitant with a drop in endocochlear potential and a susceptibility to noise-induced hearing loss under conditions that do not permanently affect age/strain-matched littermates. Here we aimed to gain an understanding of events that occur before the onset of SCBM thickening. Alport stria has normal thickness and shows levels of extracellular matrix (ECM) molecules in the SCBMs commensurate with wild-type mice. Hearing thresholds in the 3-week Alport mice do not differ from those of wild-type mice. We performed RNAseq analysis using RNA from stria vascularis isolated from 3-week Alport mice and wild type littermates. Data was processed using Ingenuity Pathway Analysis software and further distilled using manual procedures. RNAseq analysis revealed significant dysregulation of genes involved in cell adhesion, cell migration, formation of protrusions, and both actin and tubulin cytoskeletal dynamics. Overall, the data suggested changes in the cellular architecture of the stria might be apparent. To test this notion, we performed dual immunofluorescence analysis on whole mounts of the stria vascularis from these same animals stained with anti-isolectin gs-ib4 (endothelial cell marker) and anti-desmin (pericyte marker) antibodies. The results showed evidence of pericyte detachment and migration as well as the formation of membrane ruffling on pericytes in z-stacked confocal images from Alport mice compared to wild type littermates. This was confirmed by TEM analysis. Earlier work from our lab showed that endothelin A receptor blockade prevents SCBM thickening and ECM accumulation in the SCBMs. Treating cultured pericytes with endothelin-1 induced actin cytoskeletal rearrangement, increasing the ratio of filamentous to globular actin. Collectively, these findings suggest that the change in type IV collagen composition in the Alport SCBMs results in cellular insult to the pericyte compartment, activating detachment and altered cytoskeletal dynamics. These events precede SCBM thickening and hearing loss in Alport mice, and thus constitute the earliest event so far recognized in Alport strial pathology.
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Affiliation(s)
- Brianna Dufek
- Boys Town National Research Hospital, Omaha, NE, USA
| | | | | | | | - Jacob Madison
- Boys Town National Research Hospital, Omaha, NE, USA
| | - Xiourui Shi
- Oregon Health Science Center, Portland, OR, USA
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18
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The nuclear transcription factor FoxG1 affects the sensitivity of mimetic aging hair cells to inflammation by regulating autophagy pathways. Redox Biol 2019; 28:101364. [PMID: 31731101 PMCID: PMC6920089 DOI: 10.1016/j.redox.2019.101364] [Citation(s) in RCA: 117] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2019] [Revised: 10/22/2019] [Accepted: 10/27/2019] [Indexed: 12/18/2022] Open
Abstract
Inflammation is a self-defense response to protect individuals from infection and tissue damage, but excessive or persistent inflammation can have adverse effects on cell survival. Many individuals become especially susceptible to chronic-inflammation-induced sensorineural hearing loss as they age, but the intrinsic molecular mechanism behind aging individuals' increased risk of hearing loss remains unclear. FoxG1 (forkhead box transcription factor G1) is a key transcription factor that plays important roles in hair cell survival through the regulation of mitochondrial function, but how the function of FoxG1 changes during aging and under inflammatory conditions is unknown. In this study, we first found that FoxG1 expression and autophagy both increased gradually in the low concentration lipopolysaccharide (LPS)-induced inflammation model, while after high concentration of LPS treatment both FoxG1 expression and autophagy levels decreased as the concentration of LPS increased. We then used siRNA to downregulate Foxg1 expression in hair cell-like OC-1 cells and found that cell death and apoptosis were significantly increased after LPS injury. Furthermore, we used d-galactose (D-gal) to create an aging model with hair cell-like OC-1 cells and cochlear explant cultures in vitro and found that the expression of Foxg1 and the level of autophagy were both decreased after D-gal and LPS co-treatment. Lastly, we knocked down the expression of Foxg1 under aged inflammation conditions and found increased numbers of dead and apoptotic cells. Together these results suggest that FoxG1 affects the sensitivity of mimetic aging hair cells to inflammation by regulating autophagy pathways.
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