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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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Klos B, Steinbach C, Ketel J, Lambert C, Penders J, Doré J, Enck P, Mack I. Effects of isolation and confinement on gastrointestinal microbiota-a systematic review. Front Nutr 2023; 10:1214016. [PMID: 37492598 PMCID: PMC10364611 DOI: 10.3389/fnut.2023.1214016] [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: 04/28/2023] [Accepted: 06/21/2023] [Indexed: 07/27/2023] Open
Abstract
Purpose The gastrointestinal (GI) microbiota is a complex and dynamic ecosystem whose composition and function are influenced by many internal and external factors. Overall, the individual GI microbiota composition appears to be rather stable but can be influenced by extreme shifts in environmental exposures. To date, there is no systematic literature review that examines the effects of extreme environmental conditions, such as strict isolation and confinement, on the GI microbiota. Methods We conducted a systematic review to examine the effects of isolated and confined environments on the human GI microbiota. The literature search was conducted according to PRISMA criteria using PubMed, Web of Science and Cochrane Library. Relevant studies were identified based on exposure to isolated and confined environments, generally being also antigen-limited, for a minimum of 28 days and classified according to the microbiota analysis method (cultivation- or molecular based approaches) and the isolation habitat (space, space- or microgravity simulation such as MARS-500 or natural isolation such as Antarctica). Microbial shifts in abundance, alpha diversity and community structure in response to isolation were assessed. Results Regardless of the study habitat, inconsistent shifts in abundance of 40 different genera, mainly in the phylum Bacillota (formerly Firmicutes) were reported. Overall, the heterogeneity of studies was high. Reducing heterogeneity was neither possible by differentiating the microbiota analysis methods nor by subgrouping according to the isolation habitat. Alpha diversity evolved non-specifically, whereas the microbial community structure remained dissimilar despite partial convergence. The GI ecosystem returned to baseline levels following exposure, showing resilience irrespective of the experiment length. Conclusion An isolated and confined environment has a considerable impact on the GI microbiota composition in terms of diversity and relative abundances of dominant taxa. However, due to a limited number of studies with rather small sample sizes, it is important to approach an in-depth conclusion with caution, and results should be considered as a preliminary trend. The risk of dysbiosis and associated diseases should be considered when planning future projects in extreme environments. Systematic review registration https://www.crd.york.ac.uk/prospero/, identifier CRD42022357589.
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Affiliation(s)
- Bea Klos
- Department of Psychosomatic Medicine and Psychotherapy, University Hospital Tübingen, Tübingen, Germany
| | - Christina Steinbach
- Department of Psychosomatic Medicine and Psychotherapy, University Hospital Tübingen, Tübingen, Germany
| | - Jasmin Ketel
- Department of Psychosomatic Medicine and Psychotherapy, University Hospital Tübingen, Tübingen, Germany
| | - Claude Lambert
- CIRI–Immunology Lab University Hospital, Saint-Étienne, France
- LCOMS/ENOSIS Université de Lorraine, Metz, France
| | - John Penders
- Department of Medical Microbiology, Infectious Diseases and Infection Prevention, Maastricht University Medical Center, CAPHRI Care and Public Health Research Institute, Maastricht, Netherlands
- Department of Medical Microbiology, Infectious Diseases and Infection Prevention, Maastricht University Medical Center, School of Nutrition and Translational Research in Metabolism, Maastricht, Netherlands
| | - Joël Doré
- UMR Micalis Institut, INRA, Paris-Saclay University, Jouy-En-Josas, France
| | - Paul Enck
- Department of Psychosomatic Medicine and Psychotherapy, University Hospital Tübingen, Tübingen, Germany
| | - Isabelle Mack
- Department of Psychosomatic Medicine and Psychotherapy, University Hospital Tübingen, Tübingen, Germany
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Tang H, Huang W, Yao YF. The metabolites of lactic acid bacteria: classification, biosynthesis and modulation of gut microbiota. MICROBIAL CELL (GRAZ, AUSTRIA) 2023; 10:49-62. [PMID: 36908281 PMCID: PMC9993431 DOI: 10.15698/mic2023.03.792] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 01/11/2023] [Accepted: 01/17/2023] [Indexed: 03/14/2023]
Abstract
Lactic acid bacteria (LAB) are ubiquitous microorganisms that can colonize the intestine and participate in the physiological metabolism of the host. LAB can produce a variety of metabolites, including organic acids, bacteriocin, amino acids, exopolysaccharides and vitamins. These metabolites are the basis of LAB function and have a profound impact on host health. The intestine is colonized by a large number of gut microorganisms with high species diversity. Metabolites of LAB can keep the balance and stability of gut microbiota through aiding in the maintenance of the intestinal epithelial barrier, resisting to pathogens and regulating immune responses, which further influence the nutrition, metabolism and behavior of the host. In this review, we summarize the metabolites of LAB and their influence on the intestine. We also discuss the underlying regulatory mechanisms and emphasize the link between LAB and the human gut from the perspective of health promotion.
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Affiliation(s)
- Huang Tang
- Shanghai Institute of Immunology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China.,Laboratory of Bacterial Pathogenesis, Department of Microbiology and Immunology, Institutes of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Wanqiu Huang
- Shanghai Institute of Immunology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China.,Laboratory of Bacterial Pathogenesis, Department of Microbiology and Immunology, Institutes of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Yu-Feng Yao
- Shanghai Institute of Immunology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China.,Laboratory of Bacterial Pathogenesis, Department of Microbiology and Immunology, Institutes of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China.,Department of Infectious Diseases, Shanghai Ruijin Hospital, Shanghai 200025, China.,State Key Laboratory of Microbial Metabolism, and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China.,Shanghai Key Laboratory of Emergency Prevention, Diagnosis and Treatment of Respiratory Infectious Diseases (20dz2261100), Shanghai 200025, China
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Buchenauer L, Junge KM, Haange SB, Simon JC, von Bergen M, Hoh AL, Aust G, Zenclussen AC, Stangl GI, Polte T. Glyphosate differentially affects the allergic immune response across generations in mice. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 850:157973. [PMID: 35963408 DOI: 10.1016/j.scitotenv.2022.157973] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 06/24/2022] [Accepted: 08/07/2022] [Indexed: 06/15/2023]
Abstract
Exposure to environmental pollutants via food, particularly during the prenatal and early postnatal periods, has been linked to adverse effects on the immune system. Among these pollutants, the widely used pesticide glyphosate has been associated with endocrine disruption, autism, and cancer. Occupational high exposure to glyphosate has also been shown to influence immune function and exacerbate allergic asthma. However, there are no studies investigating the effect of a common low-dose glyphosate exposure on the allergic immune response - neither directly nor across generations. We therefore explored the impact of oral low-dose glyphosate exposure (0.5 and 50 mg/kg body weight/day) on airway inflammation in dams (F0) and the offspring (F1 and F2 generations) using a murine multi-generational asthma model. While exposure to 50 mg/kg glyphosate induced a mild eosinophilic infiltration in the bronchoalveolar lavage and TH2 cytokine production in the dams, the F1 offspring developed a reduced immune response after maternal exposure to 0.5 mg/kg glyphosate. In particular, decreased lung inflammation, HDM-specific IgE levels, and asthma-relevant cytokine production were primarily observed in the female F1 offspring. However, not only the TH2 cytokines IL-13 and IL-5 but also the TH17 cytokine IL-17 and TH1 cytokine IFN-γ were reduced indicating a more general immunosuppressive function. Notably, the dampened immune response was no longer observed in the female F2 generation. Furthermore, female F1 offspring showed an increased abundance of bacteria in the gut, which have been associated with probiotic-mediated reduced allergic immune responses. Our results suggest a potential immunosuppressive effect of low-dose maternal glyphosate exposure in the F1 offspring that might be mediated by an altered microbiota composition. Further studies are needed to explore if this type of immune response modulation might also be associated with impairments in immune defense upon infectious diseases or even cancer pathology.
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Affiliation(s)
- Lisa Buchenauer
- Helmholtz Centre for Environmental Research - UFZ, Department of Environmental Immunology, Leipzig, Germany; Department of Dermatology, Venerology and Allergology, Leipzig University Medical Center, University of Leipzig, Leipzig, Germany
| | - Kristin M Junge
- Helmholtz Centre for Environmental Research - UFZ, Department of Environmental Immunology, Leipzig, Germany
| | - Sven-Bastiaan Haange
- Helmholtz Centre for Environmental Research - UFZ, Department of Molecular Systems Biology, Leipzig, Germany
| | - Jan C Simon
- Department of Dermatology, Venerology and Allergology, Leipzig University Medical Center, University of Leipzig, Leipzig, Germany
| | - Martin von Bergen
- Helmholtz Centre for Environmental Research - UFZ, Department of Molecular Systems Biology, Leipzig, Germany; University of Leipzig, Faculty of Life Sciences, Institute of Biochemistry, Leipzig, Germany; German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany
| | - Anna-Lena Hoh
- Research Laboratories and Clinic of Visceral, Transplantation, Thoracic, and Vascular Surgery, Leipzig University and University Hospital Leipzig, 04103 Leipzig, Germany
| | - Gabriela Aust
- Research Laboratories and Clinic of Visceral, Transplantation, Thoracic, and Vascular Surgery, Leipzig University and University Hospital Leipzig, 04103 Leipzig, Germany
| | - Ana C Zenclussen
- Helmholtz Centre for Environmental Research - UFZ, Department of Environmental Immunology, Leipzig, Germany; Perinatal Immunology, Saxonian Incubator for Clinical Translation (SIKT), Medical Faculty, University Leipzig, 04103 Leipzig, Germany
| | - Gabriele I Stangl
- Institute of Agriculture and Nutritional Sciences, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
| | - Tobias Polte
- Helmholtz Centre for Environmental Research - UFZ, Department of Environmental Immunology, Leipzig, Germany; Department of Dermatology, Venerology and Allergology, Leipzig University Medical Center, University of Leipzig, Leipzig, Germany.
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Jiang CH, Fang X, Huang W, Guo JY, Chen JY, Wu HY, Li ZS, Zou WB, Liao Z. Alterations in the Gut Microbiota and Metabolomics of Seafarers after a Six-Month Sea Voyage. Microbiol Spectr 2022; 10:e0189922. [PMID: 36197290 PMCID: PMC9603232 DOI: 10.1128/spectrum.01899-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2022] [Accepted: 09/15/2022] [Indexed: 12/31/2022] Open
Abstract
Maintaining the health of seafarers is a difficult task during long-term voyages. Little is known about the corresponding changes in the gut microbiome-host interaction. This study recruited 30 seafarers undertaking a 6-month voyage and analyzed their gut microbiota using 16S rRNA gene sequencing. Fecal untargeted metabolomics analysis was performed using liquid chromatography-mass spectrometry. Significant changes in the composition of the gut microbiota and an increased ratio of Firmicutes/Bacteroidetes at the end (day 180) of the 6-month voyage, relative to the start (day 0), were observed. At the genus level, the abundances of Holdemanella and Plesiomonas were significantly increased, while the abundance of Bacteroides was decreased. Predicted microbial functional analysis revealed significant decreases in folate biosynthesis and biotin metabolism. Furthermore, 20 differential metabolites within six differentially enriched human metabolic pathways (including arginine biosynthesis, lysine degradation, phenylalanine metabolism, sphingolipid metabolism, pentose and glucuronate interconversions, and glycine, serine, and threonine metabolism) were identified by comparing the fecal metabolites at day 0 and day 180. Spearman correlation analysis revealed close relationships between the 14 differential microbiota members and the six differential fecal metabolites that might affect specific human metabolic pathways. This study adopted a multi-omics approach and provides potential targets for maintaining the health of seafarers during long-term voyages. These findings are worthy of more in-depth exploration in future studies. IMPORTANCE Maintaining the health of seafarers undertaking long-term voyages is a difficult task. Apart from the alterations in the gut microbiome and fecal metabolites after a long-term voyage, our study also revealed that 20 differential metabolites within six differentially enriched human metabolic pathways are worthy of attention. Moreover, we found close relationships between the 14 differential microbiota members and the six differential fecal metabolites that might impact specific human metabolic pathways. Accordingly, preventative measures, such as adjusting the gut microbiota by decreasing potential pathobionts or increasing potential probiotics as well as offsetting the decrease in B vitamins and beneficial metabolites (e.g., d-glucuronic acid and citrulline) via dietary adjustment or nutritional supplements, might improve the health of seafarers during long-term sea voyages. These findings provide valuable clues about gut microbiome-host interactions and propose potential targets for maintaining the health of seafarers engaged in long-term sea voyages.
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Affiliation(s)
- Chun-Hui Jiang
- Department of Gastroenterology, Digestive Endoscopy Center, Changhai Hospital, Shanghai, China
- Shanghai Institute of Pancreatic Diseases, Shanghai, China
| | - Xue Fang
- Department of Gastroenterology, Digestive Endoscopy Center, Changhai Hospital, Shanghai, China
| | - Wen Huang
- Department of Gastroenterology, Digestive Endoscopy Center, Changhai Hospital, Shanghai, China
| | - Ji-Yao Guo
- Department of Gastroenterology, Digestive Endoscopy Center, Changhai Hospital, Shanghai, China
| | - Jia-Yun Chen
- Department of Gastroenterology, Digestive Endoscopy Center, Changhai Hospital, Shanghai, China
| | - Hong-Yu Wu
- Shanghai Institute of Pancreatic Diseases, Shanghai, China
| | - Zhao-Shen Li
- Department of Gastroenterology, Digestive Endoscopy Center, Changhai Hospital, Shanghai, China
- Shanghai Institute of Pancreatic Diseases, Shanghai, China
| | - Wen-Bin Zou
- Department of Gastroenterology, Digestive Endoscopy Center, Changhai Hospital, Shanghai, China
- Shanghai Institute of Pancreatic Diseases, Shanghai, China
| | - Zhuan Liao
- Department of Gastroenterology, Digestive Endoscopy Center, Changhai Hospital, Shanghai, China
- Shanghai Institute of Pancreatic Diseases, Shanghai, China
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Siddiqui R, Mungroo MR, Alharbi AM, Alfahemi H, Khan NA. The Use of Gut Microbial Modulation Strategies as Interventional Strategies for Ageing. Microorganisms 2022; 10:microorganisms10091869. [PMID: 36144471 PMCID: PMC9506335 DOI: 10.3390/microorganisms10091869] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 09/07/2022] [Accepted: 09/14/2022] [Indexed: 11/16/2022] Open
Abstract
Gut microbial composition codevelops with the host from birth and is influenced by several factors, including drug use, radiation, psychological stress, dietary changes and physical stress. Importantly, gut microbial dysbiosis has been clearly associated with several diseases, including cancer, rheumatoid arthritis and Clostridium difficile-associated diarrhoea, and is known to affect human health and performance. Herein, we discuss that a shift in the gut microbiota with age and reversal of age-related modulation of the gut microbiota could be a major contributor to the incidence of numerous age-related diseases or overall human performance. In addition, it is suggested that the gut microbiome of long-lived animals such as reptiles should be investigated for their unique properties and contribution to the potent defense system of these species could be extrapolated for the benefit of human health. A range of techniques can be used to modulate the gut microbiota to have higher abundance of “beneficial” microbes that have been linked with health and longevity.
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Affiliation(s)
- Ruqaiyyah Siddiqui
- College of Arts and Sciences, American University of Sharjah, Sharjah P.O. Box 26666, United Arab Emirates
| | - Mohammad Ridwane Mungroo
- Department of Clinical Sciences, College of Medicine, University of Sharjah, Sharjah P.O. Box 27272, United Arab Emirates
| | - Ahmad M. Alharbi
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, Taif University, Taif 21944, Saudi Arabia
| | - Hasan Alfahemi
- Department of Medical Microbiology, Faculty of Medicine, Al-Baha University, Al-Baha 65799, Saudi Arabia
| | - Naveed Ahmed Khan
- Department of Clinical Sciences, College of Medicine, University of Sharjah, Sharjah P.O. Box 27272, United Arab Emirates
- Correspondence:
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