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Jones TB, Chu P, Wilkey B, Lynch L, Jentarra G. Regional Differences in Microbial Infiltration of Brain Tissue from Alzheimer's Disease Patients and Control Individuals. Brain Sci 2024; 14:677. [PMID: 39061418 PMCID: PMC11274863 DOI: 10.3390/brainsci14070677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2024] [Revised: 06/29/2024] [Accepted: 07/01/2024] [Indexed: 07/28/2024] Open
Abstract
Alzheimer's disease (AD) is characterized by cognitive decline and neuropathology including amyloid beta (Aβ) plaques and neurofibrillary tangles (tau). Factors initiating or driving these pathologies remain unclear, though microbes have been increasingly implicated. Our data and others' findings indicate that microbes may be common constituents of the brain. It is notable that Aβ and tau have antimicrobial properties, suggesting a response to microbes in the brain. We used 16S rRNA sequencing to compare major bacterial phyla in post-mortem tissues from individuals exhibiting a range of neuropathology and cognitive status in two brain regions variably affected in AD. Our data indicate that strong regional differences exist, driven in part by the varied presence of Proteobacteria and Firmicutes. We confirmed our data using ELISA of bacterial lipopolysaccharide (LPS) and lipoteichoic acid in the same brain tissue. We identified a potential association between the composition of phyla and the presence of neuropathology but not cognitive status. Declining cognition and increasing pathology correlated closely with serum LPS, but not brain levels of LPS, although brain LPS showed a strong negative correlation with cerebral amyloid angiopathy. Collectively, our data suggest a region-specific heterogeneity of microbial populations in brain tissue potentially associated with neurodegenerative pathology.
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Affiliation(s)
- T. Bucky Jones
- College of Graduate Studies, Midwestern University, Glendale, AZ 85308, USA; (T.B.J.); (P.C.); (L.L.)
- Arizona College of Osteopathic Medicine, Midwestern University, Glendale, AZ 85308, USA;
| | - Ping Chu
- College of Graduate Studies, Midwestern University, Glendale, AZ 85308, USA; (T.B.J.); (P.C.); (L.L.)
| | - Brooke Wilkey
- Arizona College of Osteopathic Medicine, Midwestern University, Glendale, AZ 85308, USA;
- School of Medicine, Creighton University, Phoenix, AZ 85012, USA
| | - Leigha Lynch
- College of Graduate Studies, Midwestern University, Glendale, AZ 85308, USA; (T.B.J.); (P.C.); (L.L.)
| | - Garilyn Jentarra
- College of Graduate Studies, Midwestern University, Glendale, AZ 85308, USA; (T.B.J.); (P.C.); (L.L.)
- Arizona College of Osteopathic Medicine, Midwestern University, Glendale, AZ 85308, USA;
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Ko YK, Kim E, Lee EJ, Nam SJ, Kim Y, Kim S, Choi SY, Kim HY, Choi Y. Enrichment of infection-associated bacteria in the low biomass brain bacteriota of Alzheimer's disease patients. PLoS One 2024; 19:e0296307. [PMID: 38335187 PMCID: PMC10857729 DOI: 10.1371/journal.pone.0296307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Accepted: 12/08/2023] [Indexed: 02/12/2024] Open
Abstract
Alzheimer's disease (AD) is a neurodegenerative disease accompanied by neuroimmune inflammation in the frontal cortex and hippocampus. Recently, the presence of bacteria in AD-affected brains has been documented, prompting speculation about their potential role in AD-associated neuroinflammation. However, the characterization of bacteriota in human brains affected by AD remains inconclusive. This study aimed to investigate potential associations between specific bacteria and AD pathology by examining brain tissues from AD-associated neurodegenerative regions (frontal cortex and hippocampus) and the non-AD-associated hypothalamus. Employing 16S rRNA gene sequencing, 30 postmortem brain tissue samples from four individuals with normal brain histology (N) and four AD patients were analyzed, along with three blank controls. A remarkably low biomass characterized the brain bacteriota, with their overall structures delineated primarily by brain regions rather than the presence of AD. While most analyzed parameters exhibited no significant distinction in the brain bacteriota between the N and AD groups, the unique detection of Cloacibacterium normanense in the AD-associated neurodegenerative regions stood out. Additionally, infection-associated bacteria, as opposed to periodontal pathogens, were notably enriched in AD brains. This study's findings provide valuable insights into potential link between bacterial infection and neuroinflammation in AD.
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Affiliation(s)
- Yeon Kyeong Ko
- Department of Immunology and Molecular Microbiology, School of Dentistry and Dental Research Institute, Seoul National University, Seoul, Republic of Korea
| | - Eunbi Kim
- Department of Immunology and Molecular Microbiology, School of Dentistry and Dental Research Institute, Seoul National University, Seoul, Republic of Korea
| | - Eun-Jae Lee
- Department of Neurology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea
| | - Soo Jeong Nam
- Department of Pathology, Asan Medical Center, Seoul, Republic of Korea
| | - Yeshin Kim
- Department of Neurology, Kangwon National University Hospital, Kangwon National University College of Medicine, Chuncheon, Republic of Korea
| | - Seongheon Kim
- Department of Neurology, Kangwon National University Hospital, Kangwon National University College of Medicine, Chuncheon, Republic of Korea
| | - Se-Young Choi
- Department of Physiology, Dental Research Institute, Seoul National University School of Dentistry, Seoul, Republic of Korea
| | - Hyun Young Kim
- Department of Immunology and Molecular Microbiology, School of Dentistry and Dental Research Institute, Seoul National University, Seoul, Republic of Korea
| | - Youngnim Choi
- Department of Immunology and Molecular Microbiology, School of Dentistry and Dental Research Institute, Seoul National University, Seoul, Republic of Korea
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Moné Y, Earl JP, Król JE, Ahmed A, Sen B, Ehrlich GD, Lapides JR. Evidence supportive of a bacterial component in the etiology for Alzheimer's disease and for a temporal-spatial development of a pathogenic microbiome in the brain. Front Cell Infect Microbiol 2023; 13:1123228. [PMID: 37780846 PMCID: PMC10534976 DOI: 10.3389/fcimb.2023.1123228] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Accepted: 07/05/2023] [Indexed: 10/03/2023] Open
Abstract
Background Over the last few decades, a growing body of evidence has suggested a role for various infectious agents in Alzheimer's disease (AD) pathogenesis. Despite diverse pathogens (virus, bacteria, fungi) being detected in AD subjects' brains, research has focused on individual pathogens and only a few studies investigated the hypothesis of a bacterial brain microbiome. We profiled the bacterial communities present in non-demented controls and AD subjects' brains. Results We obtained postmortem samples from the brains of 32 individual subjects, comprising 16 AD and 16 control age-matched subjects with a total of 130 samples from the frontal and temporal lobes and the entorhinal cortex. We used full-length 16S rRNA gene amplification with Pacific Biosciences sequencing technology to identify bacteria. We detected bacteria in the brains of both cohorts with the principal bacteria comprising Cutibacterium acnes (formerly Propionibacterium acnes) and two species each of Acinetobacter and Comamonas genera. We used a hierarchical Bayesian method to detect differences in relative abundance among AD and control groups. Because of large abundance variances, we also employed a new analysis approach based on the Latent Dirichlet Allocation algorithm, used in computational linguistics. This allowed us to identify five sample classes, each revealing a different microbiota. Assuming that samples represented infections that began at different times, we ordered these classes in time, finding that the last class exclusively explained the existence or non-existence of AD. Conclusions The AD-related pathogenicity of the brain microbiome seems to be based on a complex polymicrobial dynamic. The time ordering revealed a rise and fall of the abundance of C. acnes with pathogenicity occurring for an off-peak abundance level in association with at least one other bacterium from a set of genera that included Methylobacterium, Bacillus, Caulobacter, Delftia, and Variovorax. C. acnes may also be involved with outcompeting the Comamonas species, which were strongly associated with non-demented brain microbiota, whose early destruction could be the first stage of disease. Our results are also consistent with a leaky blood-brain barrier or lymphatic network that allows bacteria, viruses, fungi, or other pathogens to enter the brain.
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Affiliation(s)
- Yves Moné
- Department of Microbiology and Immunology, Centers for Genomic Sciences and Advanced Microbial Processing, Drexel University College of Medicine, Philadelphia, PA, United States
| | - Joshua P Earl
- Department of Microbiology and Immunology, Centers for Genomic Sciences and Advanced Microbial Processing, Drexel University College of Medicine, Philadelphia, PA, United States
| | - Jarosław E Król
- Department of Microbiology and Immunology, Centers for Genomic Sciences and Advanced Microbial Processing, Drexel University College of Medicine, Philadelphia, PA, United States
| | - Azad Ahmed
- Department of Microbiology and Immunology, Centers for Genomic Sciences and Advanced Microbial Processing, Drexel University College of Medicine, Philadelphia, PA, United States
| | - Bhaswati Sen
- Department of Microbiology and Immunology, Centers for Genomic Sciences and Advanced Microbial Processing, Drexel University College of Medicine, Philadelphia, PA, United States
| | - Garth D Ehrlich
- Department of Microbiology and Immunology, Centers for Genomic Sciences and Advanced Microbial Processing, Drexel University College of Medicine, Philadelphia, PA, United States
| | - Jeffrey R Lapides
- Department of Microbiology and Immunology, Centers for Genomic Sciences and Advanced Microbial Processing, Drexel University College of Medicine, Philadelphia, PA, United States
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Hashimoto K. Emerging role of the host microbiome in neuropsychiatric disorders: overview and future directions. Mol Psychiatry 2023; 28:3625-3637. [PMID: 37845499 PMCID: PMC10730413 DOI: 10.1038/s41380-023-02287-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 09/23/2023] [Accepted: 09/29/2023] [Indexed: 10/18/2023]
Abstract
The human body harbors a diverse ecosystem of microorganisms, including bacteria, viruses, and fungi, collectively known as the microbiota. Current research is increasingly focusing on the potential association between the microbiota and various neuropsychiatric disorders. The microbiota resides in various parts of the body, such as the oral cavity, nasal passages, lungs, gut, skin, bladder, and vagina. The gut microbiota in the gastrointestinal tract has received particular attention due to its high abundance and its potential role in psychiatric and neurodegenerative disorders. However, the microbiota presents in other body tissues, though less abundant, also plays crucial role in immune system and human homeostasis, thus influencing the development and progression of neuropsychiatric disorders. For example, oral microbiota imbalance and associated periodontitis might increase the risk for neuropsychiatric disorders. Additionally, studies using the postmortem brain samples have detected the widespread presence of oral bacteria in the brains of patients with Alzheimer's disease. This article provides an overview of the emerging role of the host microbiota in neuropsychiatric disorders and discusses future directions, such as underlying biological mechanisms, reliable biomarkers associated with the host microbiota, and microbiota-targeted interventions, for research in this field.
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Affiliation(s)
- Kenji Hashimoto
- Division of Clinical Neuroscience, Chiba University Center for Forensic Mental Health, Chiba, 260-8670, Japan.
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Latham AS, Moreno JA, Geer CE. Biological agents and the aging brain: glial inflammation and neurotoxic signaling. FRONTIERS IN AGING 2023; 4:1244149. [PMID: 37649972 PMCID: PMC10464498 DOI: 10.3389/fragi.2023.1244149] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Accepted: 08/01/2023] [Indexed: 09/01/2023]
Abstract
Neuroinflammation is a universal characteristic of brain aging and neurological disorders, irrespective of the disease state. Glial inflammation mediates this signaling, through astrocyte and microglial polarization from neuroprotective to neurotoxic phenotypes. Glial reactivity results in the loss of homeostasis, as these cells no longer provide support to neurons, in addition to the production of chronically toxic pro-inflammatory mediators. These glial changes initiate an inflammatory brain state that injures the central nervous system (CNS) over time. As the brain ages, glia are altered, including increased glial cell numbers, morphological changes, and either a pre-disposition or inability to become reactive. These alterations induce age-related neuropathologies, ultimately leading to neuronal degradation and irreversible damage associated with disorders of the aged brain, including Alzheimer's Disease (AD) and other related diseases. While the complex interactions of these glial cells and the brain are well studied, the role additional stressors, such as infectious agents, play on age-related neuropathology has not been fully elucidated. Both biological agents in the periphery, such as bacterial infections, or in the CNS, including viral infections like SARS-CoV-2, push glia into neuroinflammatory phenotypes that can exacerbate pathology within the aging brain. These biological agents release pattern associated molecular patterns (PAMPs) that bind to pattern recognition receptors (PRRs) on glial cells, beginning an inflammatory cascade. In this review, we will summarize the evidence that biological agents induce reactive glia, which worsens age-related neuropathology.
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Affiliation(s)
- Amanda S. Latham
- Department of Environmental and Radiological Health Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO, United States
- Brain Research Center, Colorado State University, Fort Collins, CO, United States
| | - Julie A. Moreno
- Department of Environmental and Radiological Health Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO, United States
- Brain Research Center, Colorado State University, Fort Collins, CO, United States
| | - Charlize E. Geer
- Department of Environmental and Radiological Health Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO, United States
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