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Fu Y, Chen W, Liu Y. The association between ultra-processed food intake and age-related hearing loss: a cross-sectional study. BMC Geriatr 2024; 24:450. [PMID: 38783172 PMCID: PMC11118724 DOI: 10.1186/s12877-024-04935-0] [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: 09/09/2023] [Accepted: 03/29/2024] [Indexed: 05/25/2024] Open
Abstract
OBJECTIVES This study aimed to explore the association between ultra-processed foods and age-related hearing loss. METHODS Cross-sectional analyses based on data from a nationally representative sample of 1075 adults aged over 50 in the US was performed. The odds ratios (ORs) and 95% confidence intervals (CIs) for hearing loss according to ultra-processed foods intake quartiles were calculated using a multiple adjusted logistic regression model. Restricted cubic spline model was used to flexibly model potential nonlinear relations between ultra-processed foods intake and possibility of hearing loss. We also explored statistical interactions and conducted subgroup analyses where they were found to be significant. RESULTS Ultra-processed foods intake was significantly correlated with high-frequency hearing loss. After controlling for all covariables, individuals in the fourth quartile of Ultra-processed foods consumption had a 2.8 times higher chance of developing high-frequency hearing loss than individuals in the first quartile of Ultra-processed foods consumption. We also found that the association was more significant in non-Hispanic whites. CONCLUSIONS This study discovered an association between Ultra-processed foods intake and the incidence of high-frequency hearing loss, which was more significant in non-Hispanic whites.
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Affiliation(s)
- Yanpeng Fu
- Department of Otorhinolaryngology Head and Neck Surgery, Second Affiliated Hospital of Nanchang University, Nanchang, China
| | - Wenyu Chen
- Interventional Cardiology Department, Second Affiliated Hospital of Nanchang University, No. 1 Minde Road, Nanchang, China
| | - Yuehui Liu
- Department of Otorhinolaryngology Head and Neck Surgery, Second Affiliated Hospital of Nanchang University, Nanchang, China.
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Caldarelli M, Rio P, Marrone A, Ocarino F, Chiantore M, Candelli M, Gasbarrini A, Gambassi G, Cianci R. Gut-Brain Axis: Focus on Sex Differences in Neuroinflammation. Int J Mol Sci 2024; 25:5377. [PMID: 38791415 PMCID: PMC11120930 DOI: 10.3390/ijms25105377] [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: 03/30/2024] [Revised: 05/11/2024] [Accepted: 05/13/2024] [Indexed: 05/26/2024] Open
Abstract
In recent years, there has been a growing interest in the concept of the "gut-brain axis". In addition to well-studied diseases associated with an imbalance in gut microbiota, such as cancer, chronic inflammation, and cardiovascular diseases, research is now exploring the potential role of gut microbial dysbiosis in the onset and development of brain-related diseases. When the function of the intestinal barrier is altered by dysbiosis, the aberrant immune system response interacts with the nervous system, leading to a state of "neuroinflammation". The gut microbiota-brain axis is mediated by inflammatory and immunological mechanisms, neurotransmitters, and neuroendocrine pathways. This narrative review aims to illustrate the molecular basis of neuroinflammation and elaborate on the concept of the gut-brain axis by virtue of analyzing the various metabolites produced by the gut microbiome and how they might impact the nervous system. Additionally, the current review will highlight how sex influences these molecular mechanisms. In fact, sex hormones impact the brain-gut microbiota axis at different levels, such as the central nervous system, the enteric nervous one, and enteroendocrine cells. A deeper understanding of the gut-brain axis in human health and disease is crucial to guide diagnoses, treatments, and preventive interventions.
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Affiliation(s)
- Mario Caldarelli
- Department of Translational Medicine and Surgery, Catholic University of Rome, Fondazione Policlinico Universitario A. Gemelli, IRCCS, 00168 Rome, Italy
| | - Pierluigi Rio
- Department of Translational Medicine and Surgery, Catholic University of Rome, Fondazione Policlinico Universitario A. Gemelli, IRCCS, 00168 Rome, Italy
| | - Andrea Marrone
- Department of Translational Medicine and Surgery, Catholic University of Rome, Fondazione Policlinico Universitario A. Gemelli, IRCCS, 00168 Rome, Italy
| | - Francesca Ocarino
- Department of Translational Medicine and Surgery, Catholic University of Rome, Fondazione Policlinico Universitario A. Gemelli, IRCCS, 00168 Rome, Italy
| | - Monica Chiantore
- Department of Translational Medicine and Surgery, Catholic University of Rome, Fondazione Policlinico Universitario A. Gemelli, IRCCS, 00168 Rome, Italy
| | - Marcello Candelli
- Department of Emergency, Anesthesiological and Reanimation Sciences, Catholic University of Rome, Fondazione Policlinico Universitario A. Gemelli, IRCCS, 00168 Rome, Italy
| | - Antonio Gasbarrini
- Department of Translational Medicine and Surgery, Catholic University of Rome, Fondazione Policlinico Universitario A. Gemelli, IRCCS, 00168 Rome, Italy
| | - Giovanni Gambassi
- Department of Translational Medicine and Surgery, Catholic University of Rome, Fondazione Policlinico Universitario A. Gemelli, IRCCS, 00168 Rome, Italy
| | - Rossella Cianci
- Department of Translational Medicine and Surgery, Catholic University of Rome, Fondazione Policlinico Universitario A. Gemelli, IRCCS, 00168 Rome, Italy
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McCuaig B, Goto Y. Immunostimulating Commensal Bacteria and Their Potential Use as Therapeutics. Int J Mol Sci 2023; 24:15644. [PMID: 37958628 PMCID: PMC10647581 DOI: 10.3390/ijms242115644] [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: 10/13/2023] [Revised: 10/24/2023] [Accepted: 10/24/2023] [Indexed: 11/15/2023] Open
Abstract
The gut microbiome is intimately intertwined with the host immune system, having effects on the systemic immune system. Dysbiosis of the gut microbiome has been linked not only to gastrointestinal disorders but also conditions of the skin, lungs, and brain. Commensal bacteria can affect the immune status of the host through a stimulation of the innate immune system, training of the adaptive immune system, and competitive exclusion of pathogens. Commensal bacteria improve immune response through the production of immunomodulating compounds such as microbe-associated molecular patterns (MAMPs), short-chain fatty acids (SCFAs), and secondary bile acids. The microbiome, especially when in dysbiosis, is plastic and can be manipulated through the introduction of beneficial bacteria or the adjustment of nutrients to stimulate the expansion of beneficial taxa. The complex nature of the gastrointestinal tract (GIT) ecosystem complicates the use of these methods, as similar treatments have various results in individuals with different residential microbiomes and differential health statuses. A more complete understanding of the interaction between commensal species, host genetics, and the host immune system is needed for effective microbiome interventions to be developed and implemented in a clinical setting.
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Affiliation(s)
- Bonita McCuaig
- Project for Host-Microbial Interactions in Symbiosis and Pathogenesis, Division of Molecular Immunology, Medical Mycology Research Center, Chiba University, Chiba 260-8673, Japan
| | - Yoshiyuki Goto
- Project for Host-Microbial Interactions in Symbiosis and Pathogenesis, Division of Molecular Immunology, Medical Mycology Research Center, Chiba University, Chiba 260-8673, Japan
- Division of Pandemic and Post-Disaster Infectious Diseases, Research Institute of Disaster Medicine, Chiba University, Chiba 260-8673, Japan
- Division of Infectious Disease Vaccine R&D, Research Institute of Disaster Medicine, Chiba University, Chiba 260-8673, Japan
- Chiba University Synergy Institute for Futuristic Mucosal Vaccine Research and Development (cSIMVa), Chiba University, Chiba 260-8673, Japan
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4
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Yin Q, Shi G, Zhu L. Association between gut microbiota and sensorineural hearing loss: a Mendelian randomization study. Front Microbiol 2023; 14:1230125. [PMID: 37915857 PMCID: PMC10616596 DOI: 10.3389/fmicb.2023.1230125] [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: 05/31/2023] [Accepted: 09/25/2023] [Indexed: 11/03/2023] Open
Abstract
Background Several recent studies speculated that the gut microbiota is associated with sensorineural hearing loss (SNHL) and proposed the concept of the gut-inner ear axis. However, the causal effect of gut microbiota on SNHL is still unknown. In this study, we performed a two-sample Mendelian randomization (MR) analysis to estimate the causal effect of gut microbiota on SNHL. Methods Gut microbiota data were obtained from the largest available genome-wide association study (n = 18,340) conducted by the MiBioGen consortium. The summary statistics of SNHL were obtained from the FinnGen consortium R8 release data (28,310 cases and 302,750 controls). The causal effects were estimated with inverse-variance weighted, MR-Egger, and weighted median. Reverse Mendelian randomization analysis was performed on the bacteria that were found to be associated with SNHL in forward Mendelian randomization analysis. We then performed sensitivity analyses, including Cochran's Q-test, MR-Egger intercept test, MR-PRESSO, cML-MA-BIC, and leave-one-out analysis, to detect heterogeneity and pleiotropy. Results The inverse-variance weighted results suggested that Lachnospiraceae (UCG001) had a significant protective effect against SNHL (odds ratio = 0.85, 95% confidence interval: 0.78-0.93, P = 6.99 × 10-4). In addition, Intestinimonas (odds ratio = 0.89, 95% confidence interval: 0.82-0.97, P = 8.53 × 10-3) presented a suggestively protective effect on SNHL. Rikenellaceae (RC9gutgroup) (odds ratio = 1.08, 95% confidence interval: 1.02-1.15, P = 0.01) and Eubacterium (hallii group) (odds ratio = 1.12, 95% confidence interval: 1.00-1.24, P = 0.048) suggestively increase the risk of SNHL. The results of the reverse MR analysis showed that there is no significant causal effect of SNHL on the gut microbiota. No significant heterogeneity of instrumental variables or pleiotropy was detected. Conclusion The evidence that the four genera mentioned above are associated with SNHL supports the hypothesis of a gut-inner ear axis. Our study provides microbial markers for the prevention and treatment of SNHL, and further studies are needed to explore the mechanisms of the gut microbiome-inner ear axis in health and diseases.
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Affiliation(s)
- Qiuyuan Yin
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, School of Life Sciences, Yunnan University, Kunming, Yunnan, China
| | - Guolin Shi
- Department of Neurosurgery, The Second Affiliated Hospital of Kunming Medical University, Kunming, Yunnan, China
| | - Lei Zhu
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, School of Life Sciences, Yunnan University, Kunming, Yunnan, China
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Godur DA, Denton AJ, Eshraghi N, Mittal J, Cooper J, Moosa M, Mittal R. Modulation of Gut Microbiome as a Therapeutic Modality for Auditory Disorders. Audiol Res 2023; 13:741-752. [PMID: 37887847 PMCID: PMC10603848 DOI: 10.3390/audiolres13050066] [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: 08/07/2023] [Revised: 10/04/2023] [Accepted: 10/06/2023] [Indexed: 10/28/2023] Open
Abstract
The gut microbiome has been shown to play a pivotal role in health and disease. Recently, there has been increased interest within the auditory community to explore the role of the gut microbiome in the auditory system and its implications for hearing disorders such as sensorineural hearing loss (SNHL), otitis media, and tinnitus. Studies have suggested that modulating the gut microbiome using probiotics as well as with diets high in monounsaturated and omega-3 fatty acids is associated with a reduction in inflammation prevalence in auditory disorders. This review aims to evaluate the current literature on modulation of the gut microbiome and its effects on otological conditions. The probiotic conversion of nondigestible carbohydrates into short-chain fatty acids has been shown to provide benefits for improving hearing by maintaining an adequate vascular supply. For acute and secretory otitis media, studies have shown that a combination therapy of probiotics with a decreased dose of antibiotics yields better clinical outcomes than aggressive antibiotic treatment alone. Gut microbiome modulation also alters neurotransmitter levels and reduces neuroinflammation, which may provide benefits for tinnitus by preventing increased neuronal activity. Further studies are warranted to evaluate the efficacy of probiotics, natural health products, and micronutrients on auditory disorders, paving the way to develop novel interventions.
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Affiliation(s)
- Dimitri A. Godur
- Department of Otolaryngology, Hearing Research and Cochlear Implant Laboratory, University of Miami Miller School of Medicine, Miami, FL 33136, USA; (D.A.G.); (A.J.D.); (N.E.); (J.M.); (J.C.); (M.M.)
| | - Alexa J. Denton
- Department of Otolaryngology, Hearing Research and Cochlear Implant Laboratory, University of Miami Miller School of Medicine, Miami, FL 33136, USA; (D.A.G.); (A.J.D.); (N.E.); (J.M.); (J.C.); (M.M.)
- Herbert Wertheim College of Medicine, Florida International University, Miami, FL 33199, USA
| | - Nicolas Eshraghi
- Department of Otolaryngology, Hearing Research and Cochlear Implant Laboratory, University of Miami Miller School of Medicine, Miami, FL 33136, USA; (D.A.G.); (A.J.D.); (N.E.); (J.M.); (J.C.); (M.M.)
| | - Jeenu Mittal
- Department of Otolaryngology, Hearing Research and Cochlear Implant Laboratory, University of Miami Miller School of Medicine, Miami, FL 33136, USA; (D.A.G.); (A.J.D.); (N.E.); (J.M.); (J.C.); (M.M.)
| | - Jaimee Cooper
- Department of Otolaryngology, Hearing Research and Cochlear Implant Laboratory, University of Miami Miller School of Medicine, Miami, FL 33136, USA; (D.A.G.); (A.J.D.); (N.E.); (J.M.); (J.C.); (M.M.)
- School of Medicine, New York Medical College, Valhalla, NY 10595, USA
| | - Moeed Moosa
- Department of Otolaryngology, Hearing Research and Cochlear Implant Laboratory, University of Miami Miller School of Medicine, Miami, FL 33136, USA; (D.A.G.); (A.J.D.); (N.E.); (J.M.); (J.C.); (M.M.)
| | - Rahul Mittal
- Department of Otolaryngology, Hearing Research and Cochlear Implant Laboratory, University of Miami Miller School of Medicine, Miami, FL 33136, USA; (D.A.G.); (A.J.D.); (N.E.); (J.M.); (J.C.); (M.M.)
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Graham AS, Ben-Azu B, Tremblay MÈ, Torre P, Senekal M, Laughton B, van der Kouwe A, Jankiewicz M, Kaba M, Holmes MJ. A review of the auditory-gut-brain axis. Front Neurosci 2023; 17:1183694. [PMID: 37600010 PMCID: PMC10435389 DOI: 10.3389/fnins.2023.1183694] [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: 03/10/2023] [Accepted: 07/17/2023] [Indexed: 08/22/2023] Open
Abstract
Hearing loss places a substantial burden on medical resources across the world and impacts quality of life for those affected. Further, it can occur peripherally and/or centrally. With many possible causes of hearing loss, there is scope for investigating the underlying mechanisms involved. Various signaling pathways connecting gut microbes and the brain (the gut-brain axis) have been identified and well established in a variety of diseases and disorders. However, the role of these pathways in providing links to other parts of the body has not been explored in much depth. Therefore, the aim of this review is to explore potential underlying mechanisms that connect the auditory system to the gut-brain axis. Using select keywords in PubMed, and additional hand-searching in google scholar, relevant studies were identified. In this review we summarize the key players in the auditory-gut-brain axis under four subheadings: anatomical, extracellular, immune and dietary. Firstly, we identify important anatomical structures in the auditory-gut-brain axis, particularly highlighting a direct connection provided by the vagus nerve. Leading on from this we discuss several extracellular signaling pathways which might connect the ear, gut and brain. A link is established between inflammatory responses in the ear and gut microbiome-altering interventions, highlighting a contribution of the immune system. Finally, we discuss the contribution of diet to the auditory-gut-brain axis. Based on the reviewed literature, we propose numerous possible key players connecting the auditory system to the gut-brain axis. In the future, a more thorough investigation of these key players in animal models and human research may provide insight and assist in developing effective interventions for treating hearing loss.
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Affiliation(s)
- Amy S. Graham
- Imaging Sciences, Neuroscience Institute, University of Cape Town, Cape Town, South Africa
- Department of Human Biology, Division of Biomedical Engineering, University of Cape Town, Cape Town, South Africa
| | - Benneth Ben-Azu
- Division of Medical Sciences, University of Victoria, Victoria, BC, Canada
- Department of Pharmacology, Faculty of Basic Medical Sciences, College of Health Sciences, Delta State University, Abraka, Delta State, Nigeria
| | - Marie-Ève Tremblay
- Division of Medical Sciences, University of Victoria, Victoria, BC, Canada
- Département de Médecine Moléculaire, Université Laval, Québec City, QC, Canada
- Axe Neurosciences, Centre de Recherche du CHU de Québec, Université Laval, Quebec City, QC, Canada
- Neurology and Neurosurgery Department, McGill University, Montreal, QC, Canada
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
- Centre for Advanced Materials and Related Technology (CAMTEC), University of Victoria, Victoria, BC, Canada
- Institute for Aging and Lifelong Health, University of Victoria, Victoria, BC, Canada
| | - Peter Torre
- School of Speech, Language, and Hearing Sciences, San Diego State University, San Diego, CA, United States
| | - Marjanne Senekal
- Department of Human Biology, Division of Physiological Sciences, University of Cape Town, Cape Town, South Africa
| | - Barbara Laughton
- Family Clinical Research Unit, Department of Pediatrics and Child Health, Stellenbosch University, Cape Town, South Africa
| | - Andre van der Kouwe
- Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA, United States
- Department of Radiology, Harvard Medical School, Boston, MA, United States
| | - Marcin Jankiewicz
- Imaging Sciences, Neuroscience Institute, University of Cape Town, Cape Town, South Africa
- Department of Human Biology, Division of Biomedical Engineering, University of Cape Town, Cape Town, South Africa
| | - Mamadou Kaba
- Department of Pathology, Division of Medical Microbiology, University of Cape Town, Cape Town, South Africa
| | - Martha J. Holmes
- Imaging Sciences, Neuroscience Institute, University of Cape Town, Cape Town, South Africa
- Department of Human Biology, Division of Biomedical Engineering, University of Cape Town, Cape Town, South Africa
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
- ImageTech, Simon Fraser University, Surrey, BC, Canada
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Celiac Disease and Neurological Manifestations: From Gluten to Neuroinflammation. Int J Mol Sci 2022; 23:ijms232415564. [PMID: 36555205 PMCID: PMC9779232 DOI: 10.3390/ijms232415564] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 12/04/2022] [Accepted: 12/06/2022] [Indexed: 12/13/2022] Open
Abstract
Celiac disease (CD) is a complex multi-organ disease with a high prevalence of extra-intestinal involvement, including neurological and psychiatric manifestations, such as cerebellar ataxia, peripheral neuropathy, epilepsy, headache, cognitive impairment, and depression. However, the mechanisms behind the neurological involvement in CD remain controversial. Recent evidence shows these can be related to gluten-mediated pathogenesis, including antibody cross-reaction, deposition of immune-complex, direct neurotoxicity, and in severe cases, vitamins or nutrients deficiency. Here, we have summarized new evidence related to gut microbiota and the so-called "gut-liver-brain axis" involved in CD-related neurological manifestations. Additionally, there has yet to be an agreement on whether serological or neurophysiological findings can effectively early diagnose and properly monitor CD-associated neurological involvement; notably, most of them can revert to normal with a rigorous gluten-free diet. Moving from a molecular level to a symptom-based approach, clinical, serological, and neurophysiology data might help to disentangle the many-faceted interactions between the gut and brain in CD. Eventually, the identification of multimodal biomarkers might help diagnose, monitor, and improve the quality of life of patients with "neuroCD".
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Age-Related Hearing Loss: The Link between Inflammaging, Immunosenescence, and Gut Dysbiosis. Int J Mol Sci 2022; 23:ijms23137348. [PMID: 35806352 PMCID: PMC9266910 DOI: 10.3390/ijms23137348] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [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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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:ijms23095179. [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] [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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