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Weber C, Dilthey A, Finzer P. The role of microbiome-host interactions in the development of Alzheimer´s disease. Front Cell Infect Microbiol 2023; 13:1151021. [PMID: 37333848 PMCID: PMC10272569 DOI: 10.3389/fcimb.2023.1151021] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Accepted: 05/16/2023] [Indexed: 06/20/2023] Open
Abstract
Alzheimer`s disease (AD) is the most prevalent cause of dementia. It is often assumed that AD is caused by an aggregation of extracellular beta-amyloid and intracellular tau-protein, supported by a recent study showing reduced brain amyloid levels and reduced cognitive decline under treatment with a beta-amyloid-binding antibody. Confirmation of the importance of amyloid as a therapeutic target notwithstanding, the underlying causes of beta-amyloid aggregation in the human brain, however, remain to be elucidated. Multiple lines of evidence point towards an important role of infectious agents and/or inflammatory conditions in the etiology of AD. Various microorganisms have been detected in the cerebrospinal fluid and brains of AD-patients and have thus been hypothesized to be linked to the development of AD, including Porphyromonas gingivalis (PG) and Spirochaetes. Intriguingly, these microorganisms are also found in the oral cavity under normal physiological conditions, which is often affected by multiple pathologies like caries or tooth loss in AD patients. Oral cavity pathologies are mostly accompanied by a compositional shift in the community of oral microbiota, mainly affecting commensal microorganisms and referred to as 'dysbiosis'. Oral dysbiosis seems to be at least partly mediated by key pathogens such as PG, and it is associated with a pro-inflammatory state that promotes the destruction of connective tissue in the mouth, possibly enabling the translocation of pathogenic microbiota from the oral cavity to the nervous system. It has therefore been hypothesized that dysbiosis of the oral microbiome may contribute to the development of AD. In this review, we discuss the infectious hypothesis of AD in the light of the oral microbiome and microbiome-host interactions, which may contribute to or even cause the development of AD. We discuss technical challenges relating to the detection of microorganisms in relevant body fluids and approaches for avoiding false-positives, and introduce the antibacterial protein lactoferrin as a potential link between the dysbiotic microbiome and the host inflammatory reaction.
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Seymour T, Zhang J. Porphyromonas Gingivalis in the Pathogenesis of Alzheimer’s Disease and Its Therapeutic Target. JOURNAL OF EXPLORATORY RESEARCH IN PHARMACOLOGY 2022; 7:45-53. [DOI: 10.14218/jerp.2021.00030] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Osorio C, Sfera A, Anton JJ, Thomas KG, Andronescu CV, Li E, Yahia RW, Avalos AG, Kozlakidis Z. Virus-Induced Membrane Fusion in Neurodegenerative Disorders. Front Cell Infect Microbiol 2022; 12:845580. [PMID: 35531328 PMCID: PMC9070112 DOI: 10.3389/fcimb.2022.845580] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 03/01/2022] [Indexed: 12/15/2022] Open
Abstract
A growing body of epidemiological and research data has associated neurotropic viruses with accelerated brain aging and increased risk of neurodegenerative disorders. Many viruses replicate optimally in senescent cells, as they offer a hospitable microenvironment with persistently elevated cytosolic calcium, abundant intracellular iron, and low interferon type I. As cell-cell fusion is a major driver of cellular senescence, many viruses have developed the ability to promote this phenotype by forming syncytia. Cell-cell fusion is associated with immunosuppression mediated by phosphatidylserine externalization that enable viruses to evade host defenses. In hosts, virus-induced immune dysfunction and premature cellular senescence may predispose to neurodegenerative disorders. This concept is supported by novel studies that found postinfectious cognitive dysfunction in several viral illnesses, including human immunodeficiency virus-1, herpes simplex virus-1, and SARS-CoV-2. Virus-induced pathological syncytia may provide a unified framework for conceptualizing neuronal cell cycle reentry, aneuploidy, somatic mosaicism, viral spreading of pathological Tau and elimination of viable synapses and neurons by neurotoxic astrocytes and microglia. In this narrative review, we take a closer look at cell-cell fusion and vesicular merger in the pathogenesis of neurodegenerative disorders. We present a "decentralized" information processing model that conceptualizes neurodegeneration as a systemic illness, triggered by cytoskeletal pathology. We also discuss strategies for reversing cell-cell fusion, including, TMEM16F inhibitors, calcium channel blockers, senolytics, and tubulin stabilizing agents. Finally, going beyond neurodegeneration, we examine the potential benefit of harnessing fusion as a therapeutic strategy in regenerative medicine.
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Affiliation(s)
- Carolina Osorio
- Department of Psychiatry, Loma Linda University, Loma Linda, CA, United States
| | - Adonis Sfera
- Department of Psychiatry, Loma Linda University, Loma Linda, CA, United States
- Department of Psychiatry, Patton State Hospital, San Bernardino, CA, United States
| | - Jonathan J. Anton
- Department of Psychiatry, Patton State Hospital, San Bernardino, CA, United States
| | - Karina G. Thomas
- Department of Psychiatry, Patton State Hospital, San Bernardino, CA, United States
| | - Christina V. Andronescu
- Medical Anthropology – Department of Anthropology, Stanford University, Stanford, CA, United States
| | - Erica Li
- School of Medicine, University of California, Riverside, Riverside, CA, United States
| | - Rayan W. Yahia
- School of Medicine, University of California, Riverside, Riverside, CA, United States
| | - Andrea García Avalos
- Universidad Nacional Autónoma de México (UNAM), Facultad de Medicina Campus, Ciudad de Mexico, Mexico
| | - Zisis Kozlakidis
- International Agency for Research on Cancer (IARC), Lyon, France
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Olsen I. Porphyromonas gingivalis-Induced Neuroinflammation in Alzheimer's Disease. Front Neurosci 2021; 15:691016. [PMID: 34720846 PMCID: PMC8551391 DOI: 10.3389/fnins.2021.691016] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 08/27/2021] [Indexed: 11/13/2022] Open
Abstract
"Chronic" periodontitis and its keystone pathogen Porphyromonas gingivalis have repeatedly been associated with Alzheimer's disease (AD). Pathological hallmarks in AD are brain accumulations of amyloid-beta and neurofibrillary tangles consisting of aggregated and hyperphosphorylated tau. In addition, neuroinflammation induced by P. gingivalis has increasingly been recognized as a factor in the pathogenesis of AD. The present mini-review discusses possible mechanisms for the induction of neuroinflammation by P. gingivalis in AD, involving factors such as pro-inflammatory mediators, amyloid-beta, tau, microglia, cathepsin B, and protein kinase R. Inflammagens of P. gingivalis such as lipopolysaccharide and gingipains are also discussed.
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Affiliation(s)
- Ingar Olsen
- Department of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway
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Moinipour N, Barati M, Sahebkar A, Iranshahy M, Shakeri A. Protective effects of curcumin against iron-induced toxicity. Curr Pharm Biotechnol 2021; 23:1020-1027. [PMID: 34521323 DOI: 10.2174/1389201022666210914122846] [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: 03/04/2021] [Revised: 08/02/2021] [Accepted: 08/05/2021] [Indexed: 11/22/2022]
Abstract
Iron is an essential element in cellular metabolism that participates in many biochemical reactions. Nevertheless, iron overload in the body is the cause of damage in some organs including liver, glands, brain, heart, gastrointestinal tract and lung. Iron chelation therapy could be considered as an effective approach for removing excess iron. Deferoxamine, deferiprone and deferasirox are three common iron chelators in clinical practice but cause several side effects. In this context, the use of curcumin, a dietary phytochemical derived from turmeric, as a natural and safe antioxidant with iron-chelating activity may be a useful strategy for the management of iron overload. This review focuses on the deleterious effect of iron accumulation in different organs of the body as well as the therapeutic potential of curcumin against iron-induced toxicity.
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Affiliation(s)
- Nastaran Moinipour
- Department of Pharmacognosy, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad. Iran
| | - Mahdi Barati
- Department of Immunology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad. Iran
| | - Amirhosein Sahebkar
- Biotechnology Research Center, Pharmaceutical Technology Institute, Mashhad University of Medical Sciences, Mashhad. Iran
| | - Milad Iranshahy
- Department of Pharmacognosy, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad. Iran
| | - Abolfazl Shakeri
- Department of Pharmacognosy, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad. Iran
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Olsen I. Can Porphyromonas gingivalis Contribute to Alzheimer's Disease Already at the Stage of Gingivitis? J Alzheimers Dis Rep 2021; 5:237-241. [PMID: 34113781 PMCID: PMC8150255 DOI: 10.3233/adr-210006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Alzheimer's disease (AD) has been associated with periodontitis, which starts as gingivitis. Similar to periodontitis, gingivitis bacteria, bacterial products, and inflammatory mediators can travel to the brain via the blood stream and promote brain inflammation. Periodontal pathogens such as Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans, both associated with AD, have been found in dental plaque of children already at the age of 3. It is suggested that these bacteria during long-term exposure may drive microglia (brain resident macrophage cells) into a pro-inflammatory M1 phase where they contribute to AD rather than protect against it. This notion comes from studies in mice showing that microglia actually can "remember" previous inflammatory challenge and become "trained" or "tolerant" to toxins like lipopolysaccharide. If gingivitis has an impact on AD, which should be verified, AD prophylaxis should start already at this pre-periodontitis stage with removal of supragingival plaque.
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Affiliation(s)
- Ingar Olsen
- Department of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway
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