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Caradonna E, Nemni R, Bifone A, Gandolfo P, Costantino L, Giordano L, Mormone E, Macula A, Cuomo M, Difruscolo R, Vanoli C, Vanoli E, Ferrara F. The Brain-Gut Axis, an Important Player in Alzheimer and Parkinson Disease: A Narrative Review. J Clin Med 2024; 13:4130. [PMID: 39064171 DOI: 10.3390/jcm13144130] [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: 04/04/2024] [Revised: 07/08/2024] [Accepted: 07/12/2024] [Indexed: 07/28/2024] Open
Abstract
Neurodegenerative diseases, such as Alzheimer's disease (AD) and Parkinson's disease (PD), are severe age-related disorders with complex and multifactorial causes. Recent research suggests a critical link between neurodegeneration and the gut microbiome, via the gut-brain communication pathway. This review examines the role of trimethylamine N-oxide (TMAO), a gut microbiota-derived metabolite, in the development of AD and PD, and investigates its interaction with microRNAs (miRNAs) along this bidirectional pathway. TMAO, which is produced from dietary metabolites like choline and carnitine, has been linked to increased neuroinflammation, protein misfolding, and cognitive decline. In AD, elevated TMAO levels are associated with amyloid-beta and tau pathologies, blood-brain barrier disruption, and neuronal death. TMAO can cross the blood-brain barrier and promote the aggregation of amyloid and tau proteins. Similarly, TMAO affects alpha-synuclein conformation and aggregation, a hallmark of PD. TMAO also activates pro-inflammatory pathways such as NF-kB signaling, exacerbating neuroinflammation further. Moreover, TMAO modulates the expression of various miRNAs that are involved in neurodegenerative processes. Thus, the gut microbiome-miRNA-brain axis represents a newly discovered mechanistic link between gut dysbiosis and neurodegeneration. MiRNAs regulate the key pathways involved in neuroinflammation, oxidative stress, and neuronal death, contributing to disease progression. As a direct consequence, specific miRNA signatures may serve as potential biomarkers for the early detection and monitoring of AD and PD progression. This review aims to elucidate the complex interrelationships between the gut microbiota, trimethylamine-N-oxide (TMAO), microRNAs (miRNAs), and the central nervous system, and the implications of these connections in neurodegenerative diseases. In this context, an overview of the current neuroradiology techniques available for studying neuroinflammation and of the animal models used to investigate these intricate pathologies will also be provided. In summary, a bulk of evidence supports the concept that modulating the gut-brain communication pathway through dietary changes, the manipulation of the microbiome, and/or miRNA-based therapies may offer novel approaches for implementing the treatment of debilitating neurological disorders.
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Affiliation(s)
- Eugenio Caradonna
- Integrated Laboratory Medicine Services, Centro Diagnostico Italiano S.p.A., 20011 Milan, Italy
| | - Raffaello Nemni
- Unit of Neurology, Centro Diagnostico Italiano S.p.A., Milan Fondazione Crespi Spano, 20011 Milan, Italy
- Nuclear Medicine Unit, Imaging Department, Centro Diagnostico Italiano S.p.A., 20011 Milan, Italy
| | - Angelo Bifone
- Department of Molecular Biotechnology and Health Sciences, University of Torino, 10124 Torino, Italy
| | - Patrizia Gandolfo
- Nuclear Medicine Unit, Imaging Department, Centro Diagnostico Italiano S.p.A., 20011 Milan, Italy
| | - Lucy Costantino
- Laboratory of Medical Genetics, Centro Diagnostico Italiano S.p.A., 20011 Milan, Italy
| | - Luca Giordano
- Laboratory of Medical Genetics, Centro Diagnostico Italiano S.p.A., 20011 Milan, Italy
| | - Elisabetta Mormone
- Institute for Stem-Cell Biology, Regenerative Medicine and Innovative Therapies (ISBReMIT), Fondazione IRCCS Casa Sollievo della Sofferenza, 71013 San Giovanni Rotondo, Italy
| | - Anna Macula
- Centro Ricerche Bracco, Bracco Imaging S.p.A., Colleretto Giacosa, 10010 Turin, Italy
- Department of Physics, University of Torino, 10124 Torino, Italy
| | - Mariarosa Cuomo
- Nuclear Medicine Unit, Imaging Department, Centro Diagnostico Italiano S.p.A., 20011 Milan, Italy
- Department of Oncology and Hemato-Oncology, University of Milan, 20122 Milan, Italy
| | | | - Camilla Vanoli
- Department of Clinical Psychology, Antioch University Los Angeles, Culver City, CA 90230, USA
| | - Emilio Vanoli
- School of Nursing, Cardiovascular Diseases, University of Pavia, 27100 Pavia, Italy
| | - Fulvio Ferrara
- Integrated Laboratory Medicine Services, Centro Diagnostico Italiano S.p.A., 20011 Milan, Italy
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McKenna MC, Choi IY, Schousboe A. Preface: Special issue: 14 th International Conference on Brain Energy Metabolism: Energy substrates and microbiome govern brain bioenergetics and cognitive function with aging. J Neurochem 2024; 168:443-449. [PMID: 38613180 DOI: 10.1111/jnc.16094] [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: 02/11/2024] [Revised: 02/22/2024] [Accepted: 02/22/2024] [Indexed: 04/14/2024]
Abstract
This Preface introduces the Special Issue entitled, "Energy Substrates and Microbiome Govern Brain Bioenergetics and Cognitive Function with Aging", which is comprised of manuscripts contributed by invited speakers and program/organizing committee members who participated in the 14th International Conference on Brain Energy Metabolism (ICBEM) held on October 24-27, 2022 in Santa Fe, New Mexico, USA. The conference covered the latest developments in research related to neuronal energetics, emerging roles for glycogen in higher brain functions, the impact of dietary intervention on aging, memory, and Alzheimer's disease, roles of the microbiome in gut-brain signaling, astrocyte-neuron interactions related to cognition and memory, novel roles for mitochondria and their metabolites, and metabolic neuroimaging in aging and neurodegeneration. The special issue contains 25 manuscripts on these topics plus three tributes to outstanding scientists who have made important contributions to brain energy metabolism and participated in numerous ICBEM conferences. In addition, two of the manuscripts describe important directions and the rationale for future research in many thematic areas covered by the conference.
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Affiliation(s)
- Mary C McKenna
- Department of Pediatrics and Program in Neuroscience, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - In-Young Choi
- Department of Neurology, Department of Radiology, Hoglund Biomedical Imaging Center, University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Arne Schousboe
- Department of Drug Design & Pharmacotherapy, School of Pharmaceutical Sciences, University of Copenhagen, Copenhagen, Denmark
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Conn KA, Borsom EM, Cope EK. Implications of microbe-derived ɣ-aminobutyric acid (GABA) in gut and brain barrier integrity and GABAergic signaling in Alzheimer's disease. Gut Microbes 2024; 16:2371950. [PMID: 39008552 PMCID: PMC11253888 DOI: 10.1080/19490976.2024.2371950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2024] [Accepted: 06/19/2024] [Indexed: 07/17/2024] Open
Abstract
The gut microbial ecosystem communicates bidirectionally with the brain in what is known as the gut-microbiome-brain axis. Bidirectional signaling occurs through several pathways including signaling via the vagus nerve, circulation of microbial metabolites, and immune activation. Alterations in the gut microbiota are implicated in Alzheimer's disease (AD), a progressive neurodegenerative disease. Perturbations in gut microbial communities may affect pathways within the gut-microbiome-brain axis through altered production of microbial metabolites including ɣ-aminobutyric acid (GABA), the primary inhibitory mammalian neurotransmitter. GABA has been shown to act on gut integrity through modulation of gut mucins and tight junction proteins and may be involved in vagus nerve signal inhibition. The GABAergic signaling pathway has been shown to be dysregulated in AD, and may be responsive to interventions. Gut microbial production of GABA is of recent interest in neurological disorders, including AD. Bacteroides and Lactic Acid Bacteria (LAB), including Lactobacillus, are predominant producers of GABA. This review highlights how temporal alterations in gut microbial communities associated with AD may affect the GABAergic signaling pathway, intestinal barrier integrity, and AD-associated inflammation.
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Affiliation(s)
- Kathryn A. Conn
- Center for Applied Microbiome Sciences, The Pathogen and Microbiome Institute, Northern Arizona University, Flagstaff, AZ, USA
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, USA
| | - Emily M. Borsom
- Center for Data-Driven Discovery for Biology, Allen Institute, Seattle, WA, USA
| | - Emily K. Cope
- Center for Applied Microbiome Sciences, The Pathogen and Microbiome Institute, Northern Arizona University, Flagstaff, AZ, USA
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, USA
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