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Ochi S, Yamada K, Saito T, Saido TC, Iinuma M, Azuma K, Kubo KY. Effects of early tooth loss on chronic stress and progression of neuropathogenesis of Alzheimer's disease in adult Alzheimer's model AppNL-G-F mice. Front Aging Neurosci 2024; 16:1361847. [PMID: 38469162 PMCID: PMC10925668 DOI: 10.3389/fnagi.2024.1361847] [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: 12/27/2023] [Accepted: 02/12/2024] [Indexed: 03/13/2024] Open
Abstract
Introduction Alzheimer's disease (AD), the most common neurodegenerative disease, is characterized by accumulated amyloid-β (Aβ) plaques, aggregated phosphorylated tau protein, gliosis-associated neuroinflammation, synaptic dysfunction, and cognitive impairment. Many cohort studies indicate that tooth loss is a risk factor for AD. The detailed mechanisms underlying the association between AD and tooth loss, however, are not yet fully understood. Methods We explored the involvement of early tooth loss in the neuropathogenesis of the adult AppNL-G-F mouse AD model. The maxillary molars were extracted bilaterally in 1-month-old male mice soon after tooth eruption. Results Plasma corticosterone levels were increased and spatial learning memory was impaired in these mice at 6 months of age. The cerebral cortex and hippocampus of AD mice with extracted teeth showed an increased accumulation of Aβ plaques and phosphorylated tau proteins, and increased secretion of the proinflammatory cytokines, including interleukin 1β (IL-1β) and tumor necrosis factor α (TNF-α), accompanied by an increased number of microglia and astrocytes, and decreased synaptophysin expression. AD mice with extracted teeth also had a shorter lifespan than the control mice. Discussion These findings revealed that long-term tooth loss is a chronic stressor, activating the recruitment of microglia and astrocytes; exacerbating neuroinflammation, Aβ deposition, phosphorylated tau accumulation, and synaptic dysfunction; and leading to spatial learning and memory impairments in AD model mice.
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Affiliation(s)
- Suzuko Ochi
- Department of Pediatric Dentistry, Asahi University School of Dentistry, Mizuho, Japan
| | - Kumiko Yamada
- Department of Health and Nutrition, Faculty of Health Science, Nagoya Women's University, Nagoya, Japan
| | - Takashi Saito
- Department of Neurocognitive Science, Institute of Brain Science, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Takaomi C Saido
- Laboratory for Proteolytic Neuroscience, RIKEN Center for Brain Science, Wako, Japan
| | - Mitsuo Iinuma
- Department of Pediatric Dentistry, Asahi University School of Dentistry, Mizuho, Japan
| | - Kagaku Azuma
- Department of Anatomy, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan
| | - Kin-Ya Kubo
- Graduate School of Human Life Science, Nagoya Women's University, Nagoya, Japan
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Pisani F, Pisani V, Arcangeli F, Harding A, Singhrao SK. Treponema denticola Has the Potential to Cause Neurodegeneration in the Midbrain via the Periodontal Route of Infection-Narrative Review. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2023; 20:6049. [PMID: 37297653 PMCID: PMC10252855 DOI: 10.3390/ijerph20116049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2023] [Revised: 03/30/2023] [Accepted: 05/29/2023] [Indexed: 06/12/2023]
Abstract
Alzheimer's disease (AD) is a neurodegenerative disease and the most common example of dementia. The neuropathological features of AD are the abnormal deposition of extracellular amyloid-β (Aβ) and intraneuronal neurofibrillary tangles with hyperphosphorylated tau protein. It is recognized that AD starts in the frontal cerebral cortex, and then it progresses to the entorhinal cortex, the hippocampus, and the rest of the brain. However, some studies on animals suggest that AD could also progress in the reverse order starting from the midbrain and then spreading to the frontal cortex. Spirochetes are neurotrophic: From a peripheral route of infection, they can reach the brain via the midbrain. Their direct and indirect effect via the interaction of their virulence factors and the microglia potentially leads to the host peripheral nerve, the midbrain (especially the locus coeruleus), and cortical damage. On this basis, this review aims to discuss the hypothesis of the ability of Treponema denticola to damage the peripheral axons in the periodontal ligament, to evade the complemental pathway and microglial immune response, to determine the cytoskeletal impairment and therefore causing the axonal transport disruption, an altered mitochondrial migration and the consequent neuronal apoptosis. Further insights about the central neurodegeneration mechanism and Treponema denticola's resistance to the immune response when aggregated in biofilm and its quorum sensing are suggested as a pathogenetic model for the advanced stages of AD.
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Affiliation(s)
- Flavio Pisani
- Faculty of Clinical and Biomedical Sciences, School of Dentistry, University of Central Lancashire, Preston PR1 2HE, UK
| | - Valerio Pisani
- IRCCS, “Santa Lucia” Foundation, Neurology and Neurorehabilitation Unit, Via Ardeatina, 306, 00179 Rome, Italy
| | - Francesca Arcangeli
- Azienda Sanitaria Locale ASLRM1, Nuovo Regina Margherita Hospital, Geriatric Department, Advanced Centre for Dementia and Cognitive Disorders, Via Emilio Morosini, 30, 00153 Rome, Italy
| | - Alice Harding
- Dementia and Neurodegenerative Disease Research Group, Faculty of Clinical and Biomedical Sciences, School of Dentistry, University of Central Lancashire, Preston PR1 2HE, UK
| | - Simarjit Kaur Singhrao
- Dementia and Neurodegenerative Disease Research Group, Faculty of Clinical and Biomedical Sciences, School of Dentistry, University of Central Lancashire, Preston PR1 2HE, UK
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Sonoda R, Kuramoto E, Minami S, Matsumoto SE, Ohyagi Y, Saito T, Saido T, Noguchi K, Goto T. Reduced Autophagy in Aged Trigeminal Neurons Causes Amyloid β Diffusion. J Dent Res 2023:220345231156095. [PMID: 36919893 DOI: 10.1177/00220345231156095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/16/2023] Open
Abstract
The relationship between oral health and the development of Alzheimer's disease (AD) in the elderly is not yet well understood. In this regard, the association between aging or neurodegeneration of the trigeminal nervous system and the accumulation of amyloid-β(1-42) (Aβ42) oligomers in the pathogenesis of AD is unknown. We focused on selective autophagy in the trigeminal mesencephalic nucleus (Vmes) and the diffusion of Aβ42 oligomers with respect to aging of the trigeminal nervous system and whether the degeneration of Vmes neurons affects the diffusion of Aβ42 oligomers. We used female 2- to 8-mo-old transgenic 3xTg-AD mice and AppNL-G-F knock-in mice and immunohistochemically examined aging-related changes in selective autophagy and Aβ42 oligomer processing in the Vmes, which exhibits high amyloid-β (Aβ) expression. We induced degeneration of Vmes neurons by extracting the maxillary molars and examined the changes in Aβ42 oligomer kinetics. Autophagosome-like membranes, which stained positive for Aβ, HO-1, and LC3B, were observed in Vmes neurons of 3xTg-AD mice, while there was weak immunoreactivity of the membranes for intraneuronal Aβ in AppNL-G-F mice. By contrast, there was strong immunopositivity for extracellular Aβ42 oligomers with the formation of Aβ42 oligomer clusters in AppNL-G-F mice. The expression of Rubicon, which indicates age-related deterioration of autophagy, increased the diffusion of Aβ42 oligomer with the age of Vmes neurons. Tooth extraction increased the extracellular immunopositivity for Aβ42 oligomers in AppNL-G-F mice. These results suggest that autophagy maintains homeostasis in Vmes neurons and that deterioration of autophagy due to aging or neurodegeneration leads to the diffusion of Aβ42 oligomers into the extracellular space and possibly the development of AD.
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Affiliation(s)
- R Sonoda
- Department of Periodontology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan.,Department of Oral Anatomy and Cell Biology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - E Kuramoto
- Department of Oral Anatomy and Cell Biology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - S Minami
- Department of Periodontology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan.,Department of Oral Anatomy and Cell Biology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - S E Matsumoto
- Department of Immunology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Y Ohyagi
- Department of Neurology and Geriatric Medicine, Ehime University Graduate School of Medicine, Ehime, Japan
| | - T Saito
- Department of Neurocognitive Science, Institute of Brain Science, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - T Saido
- Laboratory for Proteolytic Neuroscience, RIKEN Center for Brain Science, Wako, Japan
| | - K Noguchi
- Department of Periodontology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - T Goto
- Department of Oral Anatomy and Cell Biology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
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Pisani F, Pisani V, Arcangeli F, Harding A, Singhrao SK. Locus Coeruleus Dysfunction and Trigeminal Mesencephalic Nucleus Degeneration: A Cue for Periodontal Infection Mediated Damage in Alzheimer's Disease? INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2023; 20:1007. [PMID: 36673763 PMCID: PMC9858796 DOI: 10.3390/ijerph20021007] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 12/30/2022] [Accepted: 01/01/2023] [Indexed: 06/12/2023]
Abstract
Alzheimer's disease (AD) is a leading neurodegenerative disease with deteriorating cognition as its main clinical sign. In addition to the clinical history, it is characterized by the presence of two neuropathological hallmark lesions; amyloid-beta (Aβ) and neurofibrillary tangles (NFTs), identified in the brain at post-mortem in specific anatomical areas. Recently, it was discovered that NFTs occur initially in the subcortical nuclei, such as the locus coeruleus in the pons, and are said to spread from there to the cerebral cortices and the hippocampus. This contrasts with the prior acceptance of their neuropathology in the enthorinal cortex and the hippocampus. The Braak staging system places the accumulation of phosphorylated tau (p-tau) binding to NFTs in the locus coeruleus and other subcortical nuclei to precede stages I-IV. The locus coeruleus plays diverse psychological and physiological roles within the human body including rapid eye movement sleep disorder, schizophrenia, anxiety, and depression, regulation of sleep-wake cycles, attention, memory, mood, and behavior, which correlates with AD clinical behavior. In addition, the locus coeruleus regulates cardiovascular, respiratory, and gastrointestinal activities, which have only recently been associated with AD by modern day research enabling the wider understanding of AD development via comorbidities and microbial dysbiosis. The focus of this narrative review is to explore the modes of neurodegeneration taking place in the locus coeruleus during the natural aging process of the trigeminal nerve connections from the teeth and microbial dysbiosis, and to postulate a pathogenetic mechanism due to periodontal damage and/or infection focused on Treponema denticola.
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Affiliation(s)
- Flavio Pisani
- Programme Lead, MSc/MClinDent in Clinical Periodontology, Faculty of Clinical and Biomedical Sciences, School of Dentistry, University of Central Lancashire, Preston PR1 2HE, UK
| | - Valerio Pisani
- I.R.C.C.S. “Santa Lucia” Foundation, Neurology and Neurorehabilitation Unit, Via Ardeatina, 306, 00179 Rome, Italy
| | - Francesca Arcangeli
- Azienda Sanitaria Locale ASLRM1, Nuovo Regina Margherita Hospital, Geriatric Department-Advanced Centre for Dementia and Cognitive Disorders, Via Emilio Morosini, 30, 00153 Rome, Italy
| | - Alice Harding
- Dementia and Neurodegenerative Disease Research Group, Faculty of Clinical and Biomedical Sciences, School of Dentistry, University of Central Lancashire, Preston PR1 2HE, UK
| | - Sim K. Singhrao
- Dementia and Neurodegenerative Disease Research Group, Faculty of Clinical and Biomedical Sciences, School of Dentistry, University of Central Lancashire, Preston PR1 2HE, UK
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Lin Y, Ren J, McGrath C. Mechanosensitive Piezo1 and Piezo2 ion channels in craniofacial development and dentistry: Recent advances and prospects. Front Physiol 2022; 13:1039714. [PMID: 36338498 PMCID: PMC9633653 DOI: 10.3389/fphys.2022.1039714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Accepted: 10/10/2022] [Indexed: 12/04/2022] Open
Abstract
Mechanical forces play important roles in many biological processes and there is increasing interest and understanding of these roles. Mechanotransduction is the process by which mechanical stimuli are converted to biochemical signals through specific mechanisms, and this results in the activation of downstream signaling pathways with specific effects on cell behaviors. This review systematically summarizes the current understanding of the mechanosensitive Piezo1 and Piezo2 ion channels in craniofacial bone, tooth, and periodontal tissue, presenting the latest relevant evidence with implications for potential treatments and managements of dental and orofacial diseases and deformities. The mechanosensitive ion channels Piezo1 and Piezo2 are widely expressed in various cells and tissues and have essential functions in mechanosensation and mechanotransduction. These channels play an active role in many physiological and pathological processes, such as growth and development, mechano-stimulated bone homeostasis and the mediation of inflammatory responses. Emerging evidence indicates the expression of Piezo1 and Piezo2 in bone, dental tissues and dental tissue-derived stem cells and suggests that they function in dental sensation transduction, dentin mineralization and periodontal bone remodeling and modulate orthodontic tooth movement.
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